Removing individual tuple elements is not possible. There is, of course, nothing wrong with putting together another tuple with the undesired elements discarded. Show
To explicitly remove an entire tuple, just use the del statement. ExampleLive Demo #!/usr/bin/python
tup = ('physics', 'chemistry', 1997, 2000);
print tup;
del tup;
print "After deleting tup : ";
print tup;OutputThis produces the following result. Note an exception raised, this is because after del tup tuple does not exist any more − Some collection classes are mutable. The methods that add, subtract, or rearrange their members in place, and don’t return a specific item, never return the collection instance itself but def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631. Some operations are supported by several object types; in particular, practically all objects can be compared for equality, tested for truth value, and converted to a string (with the function or the slightly different function). The latter function is implicitly used when an object is written by the function. Truth Value TestingAny object can be tested for truth value, for use in an or condition or as operand of the Boolean operations below. By default, an object is considered true unless its class defines either a def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 637 method that returns def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 or a def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 639 method that returns zero, when called with the object. Here are most of the built-in objects considered false:
Operations and built-in functions that have a Boolean result always return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 642 or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 for false and def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 655 or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 for true, unless otherwise stated. (Important exception: the Boolean operations def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 657 and def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 658 always return one of their operands.) Boolean Operations — def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6 58, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6 57, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6 61These are the Boolean operations, ordered by ascending priority: Operation Result Notes def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 662 if x is false, then y, else x (1) def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 663 if x is false, then x, else y (2) def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 664 if x is false, then def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656, else def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 (3) Notes:
ComparisonsThere are eight comparison operations in Python. They all have the same priority (which is higher than that of the Boolean operations). Comparisons can be chained arbitrarily; for example, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 671 is equivalent to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 672, except that y is evaluated only once (but in both cases z is not evaluated at all when def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 673 is found to be false). This table summarizes the comparison operations: Operation Meaning def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 674 strictly less than def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 675 less than or equal def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 676 strictly greater than def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 677 greater than or equal def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 678 equal def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 679 not equal def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 680 object identity def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 681 negated object identity Objects of different types, except different numeric types, never compare equal. The def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 678 operator is always defined but for some object types (for example, class objects) is equivalent to . The def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 674, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 675, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 676 and def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 677 operators are only defined where they make sense; for example, they raise a exception when one of the arguments is a complex number. Non-identical instances of a class normally compare as non-equal unless the class defines the method. Instances of a class cannot be ordered with respect to other instances of the same class, or other types of object, unless the class defines enough of the methods , , , and (in general, and are sufficient, if you want the conventional meanings of the comparison operators). The behavior of the and operators cannot be customized; also they can be applied to any two objects and never raise an exception. Two more operations with the same syntactic priority, and , are supported by types that are or implement the >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 300 method. Numeric Types — , ,There are three distinct numeric types: integers, floating point numbers, and complex numbers. In addition, Booleans are a subtype of integers. Integers have unlimited precision. Floating point numbers are usually implemented using double in C; information about the precision and internal representation of floating point numbers for the machine on which your program is running is available in . Complex numbers have a real and imaginary part, which are each a floating point number. To extract these parts from a complex number z, use >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 305 and >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 306. (The standard library includes the additional numeric types , for rationals, and , for floating-point numbers with user-definable precision.) Numbers are created by numeric literals or as the result of built-in functions and operators. Unadorned integer literals (including hex, octal and binary numbers) yield integers. Numeric literals containing a decimal point or an exponent sign yield floating point numbers. Appending >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 309 or >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 310 to a numeric literal yields an imaginary number (a complex number with a zero real part) which you can add to an integer or float to get a complex number with real and imaginary parts. Python fully supports mixed arithmetic: when a binary arithmetic operator has operands of different numeric types, the operand with the “narrower” type is widened to that of the other, where integer is narrower than floating point, which is narrower than complex. A comparison between numbers of different types behaves as though the exact values of those numbers were being compared. The constructors , , and can be used to produce numbers of a specific type. All numeric types (except complex) support the following operations (for priorities of the operations, see ): Operation Result Notes Full documentation >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 314 sum of x and y >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 315 difference of x and y >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 316 product of x and y >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 317 quotient of x and y >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 318 floored quotient of x and y (1) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 319 remainder of >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 317 (2) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 321 x negated >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 322 x unchanged >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 323 absolute value or magnitude of x >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 325 x converted to integer (3)(6) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 327 x converted to floating point (4)(6) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 329 a complex number with real part re, imaginary part im. im defaults to zero. (6) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 331 conjugate of the complex number c >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 332 the pair >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 333 (2) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 335 x to the power y (5) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 337 x to the power y (5) Notes:
All types ( and ) also include the following operations: Operation Result x truncated to x rounded to n digits, rounding half to even. If n is omitted, it defaults to 0. the greatest <= x the least >= x For additional numeric operations see the and modules. Bitwise Operations on Integer TypesBitwise operations only make sense for integers. The result of bitwise operations is calculated as though carried out in two’s complement with an infinite number of sign bits. The priorities of the binary bitwise operations are all lower than the numeric operations and higher than the comparisons; the unary operation >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 368 has the same priority as the other unary numeric operations ( >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 369 and >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 370). This table lists the bitwise operations sorted in ascending priority: Operation Result Notes >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 371 bitwise or of x and y (4) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 372 bitwise exclusive or of x and y (4) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 373 bitwise and of x and y (4) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 374 x shifted left by n bits (1)(2) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 375 x shifted right by n bits (1)(3) >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 376 the bits of x inverted Notes:
Additional Methods on Integer TypesThe int type implements the . In addition, it provides a few more methods: int.bit_length()Return the number of bits necessary to represent an integer in binary, excluding the sign and leading zeros: >>> n = -37 >>> bin(n) '-0b100101' >>> n.bit_length() 6 More precisely, if >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 382 is nonzero, then >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 383 is the unique positive integer >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 384 such that >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 385. Equivalently, when >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 323 is small enough to have a correctly rounded logarithm, then >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 387. If >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 382 is zero, then >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 383 returns def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 642. Equivalent to: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6 New in version 3.1. int.bit_count()Return the number of ones in the binary representation of the absolute value of the integer. This is also known as the population count. Example: >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 3 Equivalent to: def bit_count(self): return bin(self).count("1") New in version 3.10. int.to_bytes(length=1, byteorder='big', *, signed=False)Return an array of bytes representing an integer. >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03' The integer is represented using length bytes, and defaults to 1. An is raised if the integer is not representable with the given number of bytes. The byteorder argument determines the byte order used to represent the integer, and defaults to >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 392. If byteorder is >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 392, the most significant byte is at the beginning of the byte array. If byteorder is >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 394, the most significant byte is at the end of the byte array. The signed argument determines whether two’s complement is used to represent the integer. If signed is def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 and a negative integer is given, an is raised. The default value for signed is def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638. The default values can be used to conveniently turn an integer into a single byte object. However, when using the default arguments, don’t try to convert a value greater than 255 or you’ll get an : >>> (65).to_bytes() b'A' Equivalent to: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order) New in version 3.2. Changed in version 3.11: Added default argument values for >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 399 and def bit_count(self): return bin(self).count("1")00.classmethod int.from_bytes(bytes, byteorder='big', *, signed=False) Return the integer represented by the given array of bytes. >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 16711680 The argument bytes must either be a or an iterable producing bytes. The byteorder argument determines the byte order used to represent the integer, and defaults to >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 392. If byteorder is >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 392, the most significant byte is at the beginning of the byte array. If byteorder is >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 394, the most significant byte is at the end of the byte array. To request the native byte order of the host system, use as the byte order value. The signed argument indicates whether two’s complement is used to represent the integer. Equivalent to: def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n New in version 3.2. Changed in version 3.11: Added default argument value for def bit_count(self): return bin(self).count("1")00.int.as_integer_ratio() Return a pair of integers whose ratio is exactly equal to the original integer and with a positive denominator. The integer ratio of integers (whole numbers) is always the integer as the numerator and def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 655 as the denominator. New in version 3.8. Additional Methods on FloatThe float type implements the . float also has the following additional methods. float.as_integer_ratio()Return a pair of integers whose ratio is exactly equal to the original float and with a positive denominator. Raises on infinities and a on NaNs. float.is_integer()Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if the float instance is finite with integral value, and def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise: >>> (-2.0).is_integer() True >>> (3.2).is_integer() False Two methods support conversion to and from hexadecimal strings. Since Python’s floats are stored internally as binary numbers, converting a float to or from a decimal string usually involves a small rounding error. In contrast, hexadecimal strings allow exact representation and specification of floating-point numbers. This can be useful when debugging, and in numerical work. float.hex()Return a representation of a floating-point number as a hexadecimal string. For finite floating-point numbers, this representation will always include a leading def bit_count(self): return bin(self).count("1")12 and a trailing def bit_count(self): return bin(self).count("1")13 and exponent.classmethod float.fromhex(s) Class method to return the float represented by a hexadecimal string s. The string s may have leading and trailing whitespace. Note that is an instance method, while is a class method. A hexadecimal string takes the form: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 60 where the optional def bit_count(self): return bin(self).count("1")16 may by either >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 369 or >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 370, def bit_count(self): return bin(self).count("1")19 and def bit_count(self): return bin(self).count("1")20 are strings of hexadecimal digits, and def bit_count(self): return bin(self).count("1")21 is a decimal integer with an optional leading sign. Case is not significant, and there must be at least one hexadecimal digit in either the integer or the fraction. This syntax is similar to the syntax specified in section 6.4.4.2 of the C99 standard, and also to the syntax used in Java 1.5 onwards. In particular, the output of is usable as a hexadecimal floating-point literal in C or Java code, and hexadecimal strings produced by C’s def bit_count(self): return bin(self).count("1")23 format character or Java’s def bit_count(self): return bin(self).count("1")24 are accepted by . Note that the exponent is written in decimal rather than hexadecimal, and that it gives the power of 2 by which to multiply the coefficient. For example, the hexadecimal string def bit_count(self): return bin(self).count("1")26 represents the floating-point number def bit_count(self): return bin(self).count("1")27, or def bit_count(self): return bin(self).count("1")28: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 61 Applying the reverse conversion to def bit_count(self): return bin(self).count("1")28 gives a different hexadecimal string representing the same number: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 62 Hashing of numeric typesFor numbers >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 382 and def bit_count(self): return bin(self).count("1")31, possibly of different types, it’s a requirement that def bit_count(self): return bin(self).count("1")32 whenever def bit_count(self): return bin(self).count("1")33 (see the method documentation for more details). For ease of implementation and efficiency across a variety of numeric types (including , , and ) Python’s hash for numeric types is based on a single mathematical function that’s defined for any rational number, and hence applies to all instances of and , and all finite instances of and . Essentially, this function is given by reduction modulo def bit_count(self): return bin(self).count("1")43 for a fixed prime def bit_count(self): return bin(self).count("1")43. The value of def bit_count(self): return bin(self).count("1")43 is made available to Python as the def bit_count(self): return bin(self).count("1")46 attribute of . CPython implementation detail: Currently, the prime used is def bit_count(self): return bin(self).count("1")48 on machines with 32-bit C longs and def bit_count(self): return bin(self).count("1")49 on machines with 64-bit C longs. Here are the rules in detail:
To clarify the above rules, here’s some example Python code, equivalent to the built-in hash, for computing the hash of a rational number, , or : def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 63 Iterator TypesPython supports a concept of iteration over containers. This is implemented using two distinct methods; these are used to allow user-defined classes to support iteration. Sequences, described below in more detail, always support the iteration methods. One method needs to be defined for container objects to provide support: container.__iter__()Return an object. The object is required to support the iterator protocol described below. If a container supports different types of iteration, additional methods can be provided to specifically request iterators for those iteration types. (An example of an object supporting multiple forms of iteration would be a tree structure which supports both breadth-first and depth-first traversal.) This method corresponds to the slot of the type structure for Python objects in the Python/C API. The iterator objects themselves are required to support the following two methods, which together form the iterator protocol: iterator.__iter__()Return the object itself. This is required to allow both containers and iterators to be used with the and statements. This method corresponds to the slot of the type structure for Python objects in the Python/C API. iterator.__next__()Return the next item from the . If there are no further items, raise the exception. This method corresponds to the slot of the type structure for Python objects in the Python/C API. Python defines several iterator objects to support iteration over general and specific sequence types, dictionaries, and other more specialized forms. The specific types are not important beyond their implementation of the iterator protocol. Once an iterator’s method raises , it must continue to do so on subsequent calls. Implementations that do not obey this property are deemed broken. Generator TypesPython’s s provide a convenient way to implement the iterator protocol. If a container object’s def bit_count(self): return bin(self).count("1")90 method is implemented as a generator, it will automatically return an iterator object (technically, a generator object) supplying the def bit_count(self): return bin(self).count("1")90 and methods. More information about generators can be found in . Sequence Types — , ,There are three basic sequence types: lists, tuples, and range objects. Additional sequence types tailored for processing of and are described in dedicated sections. Common Sequence OperationsThe operations in the following table are supported by most sequence types, both mutable and immutable. The ABC is provided to make it easier to correctly implement these operations on custom sequence types. This table lists the sequence operations sorted in ascending priority. In the table, s and t are sequences of the same type, n, i, j and k are integers and x is an arbitrary object that meets any type and value restrictions imposed by s. The def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 698 and def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 699 operations have the same priorities as the comparison operations. The >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 369 (concatenation) and >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'00 (repetition) operations have the same priority as the corresponding numeric operations. Operation Result Notes >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'01 def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if an item of s is equal to x, else def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 (1) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'04 def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 if an item of s is equal to x, else def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 (1) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'07 the concatenation of s and t (6)(7) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'08 or >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'09 equivalent to adding s to itself n times (2)(7) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'10 ith item of s, origin 0 (3) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'11 slice of s from i to j (3)(4) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'12 slice of s from i to j with step k (3)(5) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'13 length of s >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'14 smallest item of s >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'15 largest item of s >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'16 index of the first occurrence of x in s (at or after index i and before index j) (8) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'17 total number of occurrences of x in s Sequences of the same type also support comparisons. In particular, tuples and lists are compared lexicographically by comparing corresponding elements. This means that to compare equal, every element must compare equal and the two sequences must be of the same type and have the same length. (For full details see in the language reference.) Forward and reversed iterators over mutable sequences access values using an index. That index will continue to march forward (or backward) even if the underlying sequence is mutated. The iterator terminates only when an or a is encountered (or when the index drops below zero). Notes:
Immutable Sequence TypesThe only operation that immutable sequence types generally implement that is not also implemented by mutable sequence types is support for the built-in. This support allows immutable sequences, such as instances, to be used as keys and stored in and instances. Attempting to hash an immutable sequence that contains unhashable values will result in . Mutable Sequence TypesThe operations in the following table are defined on mutable sequence types. The ABC is provided to make it easier to correctly implement these operations on custom sequence types. In the table s is an instance of a mutable sequence type, t is any iterable object and x is an arbitrary object that meets any type and value restrictions imposed by s (for example, only accepts integers that meet the value restriction >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'74). Operation Result Notes >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'75 item i of s is replaced by x >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'76 slice of s from i to j is replaced by the contents of the iterable t >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'77 same as >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'78 >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'79 the elements of >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'12 are replaced by those of t (1) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'81 removes the elements of >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'12 from the list >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'83 appends x to the end of the sequence (same as >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'84) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'85 removes all items from s (same as >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'86) (5) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'87 creates a shallow copy of s (same as >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'88) (5) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'89 or >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'90 extends s with the contents of t (for the most part the same as >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'91) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'92 updates s with its contents repeated n times (6) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'93 inserts x into s at the index given by i (same as >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'94) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'95 or >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'96 retrieves the item at i and also removes it from s (2) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'97 remove the first item from s where >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'10 is equal to x (3) >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'99 reverses the items of s in place (4) Notes:
ListsLists are mutable sequences, typically used to store collections of homogeneous items (where the precise degree of similarity will vary by application). class list([iterable])Lists may be constructed in several ways:
The constructor builds a list whose items are the same and in the same order as iterable’s items. iterable may be either a sequence, a container that supports iteration, or an iterator object. If iterable is already a list, a copy is made and returned, similar to >>> (65).to_bytes() b'A'20. For example, >>> (65).to_bytes() b'A'21 returns >>> (65).to_bytes() b'A'22 and >>> (65).to_bytes() b'A'23 returns >>> (65).to_bytes() b'A'24. If no argument is given, the constructor creates a new empty list, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 649. Many other operations also produce lists, including the built-in. Lists implement all of the and sequence operations. Lists also provide the following additional method: sort(*, key=None, reverse=False)This method sorts the list in place, using only def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 674 comparisons between items. Exceptions are not suppressed - if any comparison operations fail, the entire sort operation will fail (and the list will likely be left in a partially modified state). accepts two arguments that can only be passed by keyword (): key specifies a function of one argument that is used to extract a comparison key from each list element (for example, >>> (65).to_bytes() b'A'29). The key corresponding to each item in the list is calculated once and then used for the entire sorting process. The default value of def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631 means that list items are sorted directly without calculating a separate key value. The utility is available to convert a 2.x style cmp function to a key function. reverse is a boolean value. If set to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656, then the list elements are sorted as if each comparison were reversed. This method modifies the sequence in place for economy of space when sorting a large sequence. To remind users that it operates by side effect, it does not return the sorted sequence (use to explicitly request a new sorted list instance). The method is guaranteed to be stable. A sort is stable if it guarantees not to change the relative order of elements that compare equal — this is helpful for sorting in multiple passes (for example, sort by department, then by salary grade). For sorting examples and a brief sorting tutorial, see . CPython implementation detail: While a list is being sorted, the effect of attempting to mutate, or even inspect, the list is undefined. The C implementation of Python makes the list appear empty for the duration, and raises if it can detect that the list has been mutated during a sort. TuplesTuples are immutable sequences, typically used to store collections of heterogeneous data (such as the 2-tuples produced by the built-in). Tuples are also used for cases where an immutable sequence of homogeneous data is needed (such as allowing storage in a or instance). class tuple([iterable])Tuples may be constructed in a number of ways:
The constructor builds a tuple whose items are the same and in the same order as iterable’s items. iterable may be either a sequence, a container that supports iteration, or an iterator object. If iterable is already a tuple, it is returned unchanged. For example, >>> (65).to_bytes() b'A'47 returns >>> (65).to_bytes() b'A'48 and >>> (65).to_bytes() b'A'49 returns >>> (65).to_bytes() b'A'50. If no argument is given, the constructor creates a new empty tuple, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 648. Note that it is actually the comma which makes a tuple, not the parentheses. The parentheses are optional, except in the empty tuple case, or when they are needed to avoid syntactic ambiguity. For example, >>> (65).to_bytes() b'A'52 is a function call with three arguments, while >>> (65).to_bytes() b'A'53 is a function call with a 3-tuple as the sole argument. Tuples implement all of the sequence operations. For heterogeneous collections of data where access by name is clearer than access by index, may be a more appropriate choice than a simple tuple object. RangesThe type represents an immutable sequence of numbers and is commonly used for looping a specific number of times in loops. class range(stop)class range(start, stop[, step])The arguments to the range constructor must be integers (either built-in or any object that implements the special method). If the step argument is omitted, it defaults to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 655. If the start argument is omitted, it defaults to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 642. If step is zero, is raised. For a positive step, the contents of a range >>> (65).to_bytes() b'A'62 are determined by the formula >>> (65).to_bytes() b'A'63 where >>> (65).to_bytes() b'A'64 and >>> (65).to_bytes() b'A'65. For a negative step, the contents of the range are still determined by the formula >>> (65).to_bytes() b'A'63, but the constraints are >>> (65).to_bytes() b'A'64 and >>> (65).to_bytes() b'A'68. A range object will be empty if >>> (65).to_bytes() b'A'69 does not meet the value constraint. Ranges do support negative indices, but these are interpreted as indexing from the end of the sequence determined by the positive indices. Ranges containing absolute values larger than are permitted but some features (such as ) may raise . Range examples: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 67 Ranges implement all of the sequence operations except concatenation and repetition (due to the fact that range objects can only represent sequences that follow a strict pattern and repetition and concatenation will usually violate that pattern). startThe value of the start parameter (or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 642 if the parameter was not supplied)stop The value of the stop parameter stepThe value of the step parameter (or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 655 if the parameter was not supplied) The advantage of the type over a regular or is that a object will always take the same (small) amount of memory, no matter the size of the range it represents (as it only stores the >>> (65).to_bytes() b'A'79, >>> (65).to_bytes() b'A'80 and >>> (65).to_bytes() b'A'81 values, calculating individual items and subranges as needed). Range objects implement the ABC, and provide features such as containment tests, element index lookup, slicing and support for negative indices (see ): def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 68 Testing range objects for equality with def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 678 and def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 679 compares them as sequences. That is, two range objects are considered equal if they represent the same sequence of values. (Note that two range objects that compare equal might have different , and attributes, for example >>> (65).to_bytes() b'A'88 or >>> (65).to_bytes() b'A'89.) Changed in version 3.2: Implement the Sequence ABC. Support slicing and negative indices. Test objects for membership in constant time instead of iterating through all items. Changed in version 3.3: Define ‘==’ and ‘!=’ to compare range objects based on the sequence of values they define (instead of comparing based on object identity). New in version 3.3: The , and attributes. See also
Text Sequence Type —Textual data in Python is handled with objects, or strings. Strings are immutable of Unicode code points. String literals are written in a variety of ways:
Triple quoted strings may span multiple lines - all associated whitespace will be included in the string literal. String literals that are part of a single expression and have only whitespace between them will be implicitly converted to a single string literal. That is, def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)00. See for more about the various forms of string literal, including supported escape sequences, and the >>> (65).to_bytes() b'A'62 (“raw”) prefix that disables most escape sequence processing. Strings may also be created from other objects using the constructor. Since there is no separate “character” type, indexing a string produces strings of length 1. That is, for a non-empty string s, def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)03. There is also no mutable string type, but or can be used to efficiently construct strings from multiple fragments. Changed in version 3.3: For backwards compatibility with the Python 2 series, the def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)06 prefix is once again permitted on string literals. It has no effect on the meaning of string literals and cannot be combined with the >>> (65).to_bytes() b'A'62 prefix.class str(object='')class str(object=b'', encoding='utf-8', errors='strict') Return a version of object. If object is not provided, returns the empty string. Otherwise, the behavior of def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 633 depends on whether encoding or errors is given, as follows. If neither encoding nor errors is given, def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)09 returns , which is the “informal” or nicely printable string representation of object. For string objects, this is the string itself. If object does not have a method, then falls back to returning . If at least one of encoding or errors is given, object should be a (e.g. or ). In this case, if object is a (or ) object, then def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)18 is equivalent to . Otherwise, the bytes object underlying the buffer object is obtained before calling . See and for information on buffer objects. Passing a object to without the encoding or errors arguments falls under the first case of returning the informal string representation (see also the command-line option to Python). For example: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 69 For more information on the >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'22 class and its methods, see and the section below. To output formatted strings, see the and sections. In addition, see the section. String MethodsStrings implement all of the sequence operations, along with the additional methods described below. Strings also support two styles of string formatting, one providing a large degree of flexibility and customization (see , and ) and the other based on C def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)26 style formatting that handles a narrower range of types and is slightly harder to use correctly, but is often faster for the cases it can handle (). The section of the standard library covers a number of other modules that provide various text related utilities (including regular expression support in the module). str.capitalize()Return a copy of the string with its first character capitalized and the rest lowercased. Changed in version 3.8: The first character is now put into titlecase rather than uppercase. This means that characters like digraphs will only have their first letter capitalized, instead of the full character. str.casefold()Return a casefolded copy of the string. Casefolded strings may be used for caseless matching. Casefolding is similar to lowercasing but more aggressive because it is intended to remove all case distinctions in a string. For example, the German lowercase letter def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)28 is equivalent to def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)29. Since it is already lowercase, would do nothing to def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)28; converts it to def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)29. The casefolding algorithm is described in section 3.13 of the Unicode Standard. New in version 3.3. str.center(width[, fillchar])Return centered in a string of length width. Padding is done using the specified fillchar (default is an ASCII space). The original string is returned if width is less than or equal to >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'13.str.count(sub[, start[, end]]) Return the number of non-overlapping occurrences of substring sub in the range [start, end]. Optional arguments start and end are interpreted as in slice notation. If sub is empty, returns the number of empty strings between characters which is the length of the string plus one. str.encode(encoding='utf-8', errors='strict')Return the string encoded to . encoding defaults to def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)36; see for possible values. errors controls how encoding errors are handled. If def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)37 (the default), a exception is raised. Other possible values are def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)39, def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)40, def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)41, def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)42 and any other name registered via . See for details. For performance reasons, the value of errors is not checked for validity unless an encoding error actually occurs, is enabled or a is used. Changed in version 3.1: Added support for keyword arguments. Changed in version 3.9: The value of the errors argument is now checked in and in . str.endswith(suffix[, start[, end]])Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if the string ends with the specified suffix, otherwise return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638. suffix can also be a tuple of suffixes to look for. With optional start, test beginning at that position. With optional end, stop comparing at that position.str.expandtabs(tabsize=8) Return a copy of the string where all tab characters are replaced by one or more spaces, depending on the current column and the given tab size. Tab positions occur every tabsize characters (default is 8, giving tab positions at columns 0, 8, 16 and so on). To expand the string, the current column is set to zero and the string is examined character by character. If the character is a tab ( def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)46), one or more space characters are inserted in the result until the current column is equal to the next tab position. (The tab character itself is not copied.) If the character is a newline ( def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)47) or return ( def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)48), it is copied and the current column is reset to zero. Any other character is copied unchanged and the current column is incremented by one regardless of how the character is represented when printed. >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 30str.find(sub[, start[, end]]) Return the lowest index in the string where substring sub is found within the slice def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)49. Optional arguments start and end are interpreted as in slice notation. Return >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 341 if sub is not found. Note The method should be used only if you need to know the position of sub. To check if sub is a substring or not, use the operator: >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 31str.format(*args, **kwargs) Perform a string formatting operation. The string on which this method is called can contain literal text or replacement fields delimited by braces def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 650. Each replacement field contains either the numeric index of a positional argument, or the name of a keyword argument. Returns a copy of the string where each replacement field is replaced with the string value of the corresponding argument. >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 32 See for a description of the various formatting options that can be specified in format strings. Note When formatting a number (, , , and subclasses) with the def bit_count(self): return bin(self).count("1")51 type (ex: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)59), the function temporarily sets the def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)60 locale to the def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)61 locale to decode def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)62 and def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)63 fields of def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)64 if they are non-ASCII or longer than 1 byte, and the def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)61 locale is different than the def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)60 locale. This temporary change affects other threads. Changed in version 3.7: When formatting a number with the def bit_count(self): return bin(self).count("1")51 type, the function sets temporarily the def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)60 locale to the def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)61 locale in some cases.str.format_map(mapping) Similar to def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)70, except that def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)71 is used directly and not copied to a . This is useful if for example def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)71 is a dict subclass: >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 33 New in version 3.2. str.index(sub[, start[, end]])Like , but raise when the substring is not found. str.isalnum()Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all characters in the string are alphanumeric and there is at least one character, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. A character def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)78 is alphanumeric if one of the following returns def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)80, def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)81, def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)82, or def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)83.str.isalpha() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all characters in the string are alphabetic and there is at least one character, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. Alphabetic characters are those characters defined in the Unicode character database as “Letter”, i.e., those with general category property being one of “Lm”, “Lt”, “Lu”, “Ll”, or “Lo”. Note that this is different from the “Alphabetic” property defined in the Unicode Standard.str.isascii() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if the string is empty or all characters in the string are ASCII, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. ASCII characters have code points in the range U+0000-U+007F. New in version 3.7. str.isdecimal()Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all characters in the string are decimal characters and there is at least one character, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. Decimal characters are those that can be used to form numbers in base 10, e.g. U+0660, ARABIC-INDIC DIGIT ZERO. Formally a decimal character is a character in the Unicode General Category “Nd”.str.isdigit() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all characters in the string are digits and there is at least one character, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. Digits include decimal characters and digits that need special handling, such as the compatibility superscript digits. This covers digits which cannot be used to form numbers in base 10, like the Kharosthi numbers. Formally, a digit is a character that has the property value Numeric_Type=Digit or Numeric_Type=Decimal.str.isidentifier() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if the string is a valid identifier according to the language definition, section . Call to test whether string def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)94 is a reserved identifier, such as and . Example: >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 34str.islower() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all cased characters in the string are lowercase and there is at least one cased character, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise.str.isnumeric() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all characters in the string are numeric characters, and there is at least one character, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. Numeric characters include digit characters, and all characters that have the Unicode numeric value property, e.g. U+2155, VULGAR FRACTION ONE FIFTH. Formally, numeric characters are those with the property value Numeric_Type=Digit, Numeric_Type=Decimal or Numeric_Type=Numeric.str.isprintable() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all characters in the string are printable or the string is empty, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. Nonprintable characters are those characters defined in the Unicode character database as “Other” or “Separator”, excepting the ASCII space (0x20) which is considered printable. (Note that printable characters in this context are those which should not be escaped when is invoked on a string. It has no bearing on the handling of strings written to or .)str.isspace() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if there are only whitespace characters in the string and there is at least one character, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. A character is whitespace if in the Unicode character database (see ), either its general category is >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168009 (“Separator, space”), or its bidirectional class is one of >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168010, >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168011, or >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168012.str.istitle() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if the string is a titlecased string and there is at least one character, for example uppercase characters may only follow uncased characters and lowercase characters only cased ones. Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise.str.isupper() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all cased characters in the string are uppercase and there is at least one cased character, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 35str.join(iterable) Return a string which is the concatenation of the strings in iterable. A will be raised if there are any non-string values in iterable, including objects. The separator between elements is the string providing this method. str.ljust(width[, fillchar])Return the string left justified in a string of length width. Padding is done using the specified fillchar (default is an ASCII space). The original string is returned if width is less than or equal to >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'13.str.lower() Return a copy of the string with all the cased characters converted to lowercase. The lowercasing algorithm used is described in section 3.13 of the Unicode Standard. str.lstrip([chars])Return a copy of the string with leading characters removed. The chars argument is a string specifying the set of characters to be removed. If omitted or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, the chars argument defaults to removing whitespace. The chars argument is not a prefix; rather, all combinations of its values are stripped: >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 36 See for a method that will remove a single prefix string rather than all of a set of characters. For example: >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 37static str.maketrans(x[, y[, z]]) This static method returns a translation table usable for . If there is only one argument, it must be a dictionary mapping Unicode ordinals (integers) or characters (strings of length 1) to Unicode ordinals, strings (of arbitrary lengths) or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631. Character keys will then be converted to ordinals. If there are two arguments, they must be strings of equal length, and in the resulting dictionary, each character in x will be mapped to the character at the same position in y. If there is a third argument, it must be a string, whose characters will be mapped to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631 in the result.str.partition(sep) Split the string at the first occurrence of sep, and return a 3-tuple containing the part before the separator, the separator itself, and the part after the separator. If the separator is not found, return a 3-tuple containing the string itself, followed by two empty strings. str.removeprefix(prefix, /)If the string starts with the prefix string, return >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168025. Otherwise, return a copy of the original string: >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 38 New in version 3.9. str.removesuffix(suffix, /)If the string ends with the suffix string and that suffix is not empty, return >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168026. Otherwise, return a copy of the original string: >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 39 New in version 3.9. str.replace(old, new[, count])Return a copy of the string with all occurrences of substring old replaced by new. If the optional argument count is given, only the first count occurrences are replaced. str.rfind(sub[, start[, end]])Return the highest index in the string where substring sub is found, such that sub is contained within def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)49. Optional arguments start and end are interpreted as in slice notation. Return >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 341 on failure.str.rindex(sub[, start[, end]]) Like but raises when the substring sub is not found. str.rjust(width[, fillchar])Return the string right justified in a string of length width. Padding is done using the specified fillchar (default is an ASCII space). The original string is returned if width is less than or equal to >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'13.str.rpartition(sep) Split the string at the last occurrence of sep, and return a 3-tuple containing the part before the separator, the separator itself, and the part after the separator. If the separator is not found, return a 3-tuple containing two empty strings, followed by the string itself. str.rsplit(sep=None, maxsplit=- 1)Return a list of the words in the string, using sep as the delimiter string. If maxsplit is given, at most maxsplit splits are done, the rightmost ones. If sep is not specified or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, any whitespace string is a separator. Except for splitting from the right, behaves like which is described in detail below.str.rstrip([chars]) Return a copy of the string with trailing characters removed. The chars argument is a string specifying the set of characters to be removed. If omitted or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, the chars argument defaults to removing whitespace. The chars argument is not a suffix; rather, all combinations of its values are stripped: def bit_count(self): return bin(self).count("1")0 See for a method that will remove a single suffix string rather than all of a set of characters. For example: def bit_count(self): return bin(self).count("1")1str.split(sep=None, maxsplit=- 1) Return a list of the words in the string, using sep as the delimiter string. If maxsplit is given, at most maxsplit splits are done (thus, the list will have at most >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168037 elements). If maxsplit is not specified or >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 341, then there is no limit on the number of splits (all possible splits are made). If sep is given, consecutive delimiters are not grouped together and are deemed to delimit empty strings (for example, >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168039 returns >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168040). The sep argument may consist of multiple characters (for example, >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168041 returns >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168042). Splitting an empty string with a specified separator returns >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168043. For example: def bit_count(self): return bin(self).count("1")2 If sep is not specified or is def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, a different splitting algorithm is applied: runs of consecutive whitespace are regarded as a single separator, and the result will contain no empty strings at the start or end if the string has leading or trailing whitespace. Consequently, splitting an empty string or a string consisting of just whitespace with a def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631 separator returns def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 649. For example: def bit_count(self): return bin(self).count("1")3str.splitlines(keepends=False) Return a list of the lines in the string, breaking at line boundaries. Line breaks are not included in the resulting list unless keepends is given and true. This method splits on the following line boundaries. In particular, the boundaries are a superset of . Representation Description def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)47 Line Feed def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)48 Carriage Return >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168049 Carriage Return + Line Feed >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168050 or >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168051 Line Tabulation >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168052 or >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168053 Form Feed >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168054 File Separator >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168055 Group Separator >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168056 Record Separator >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168057 Next Line (C1 Control Code) >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168058 Line Separator >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168059 Paragraph Separator Changed in version 3.2: >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168050 and >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168052 added to list of line boundaries. For example: def bit_count(self): return bin(self).count("1")4 Unlike when a delimiter string sep is given, this method returns an empty list for the empty string, and a terminal line break does not result in an extra line: def bit_count(self): return bin(self).count("1")5 For comparison, >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168063 gives: def bit_count(self): return bin(self).count("1")6str.startswith(prefix[, start[, end]]) Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if string starts with the prefix, otherwise return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638. prefix can also be a tuple of prefixes to look for. With optional start, test string beginning at that position. With optional end, stop comparing string at that position.str.strip([chars]) Return a copy of the string with the leading and trailing characters removed. The chars argument is a string specifying the set of characters to be removed. If omitted or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, the chars argument defaults to removing whitespace. The chars argument is not a prefix or suffix; rather, all combinations of its values are stripped: def bit_count(self): return bin(self).count("1")7 The outermost leading and trailing chars argument values are stripped from the string. Characters are removed from the leading end until reaching a string character that is not contained in the set of characters in chars. A similar action takes place on the trailing end. For example: def bit_count(self): return bin(self).count("1")8str.swapcase() Return a copy of the string with uppercase characters converted to lowercase and vice versa. Note that it is not necessarily true that >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168067.str.title() Return a titlecased version of the string where words start with an uppercase character and the remaining characters are lowercase. For example: def bit_count(self): return bin(self).count("1")9 The algorithm uses a simple language-independent definition of a word as groups of consecutive letters. The definition works in many contexts but it means that apostrophes in contractions and possessives form word boundaries, which may not be the desired result: >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'0 The function does not have this problem, as it splits words on spaces only. Alternatively, a workaround for apostrophes can be constructed using regular expressions: >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'1str.translate(table) Return a copy of the string in which each character has been mapped through the given translation table. The table must be an object that implements indexing via >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168069, typically a or . When indexed by a Unicode ordinal (an integer), the table object can do any of the following: return a Unicode ordinal or a string, to map the character to one or more other characters; return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, to delete the character from the return string; or raise a exception, to map the character to itself. You can use to create a translation map from character-to-character mappings in different formats. See also the module for a more flexible approach to custom character mappings. str.upper()Return a copy of the string with all the cased characters converted to uppercase. Note that >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168074 might be def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 if def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)94 contains uncased characters or if the Unicode category of the resulting character(s) is not “Lu” (Letter, uppercase), but e.g. “Lt” (Letter, titlecase). The uppercasing algorithm used is described in section 3.13 of the Unicode Standard. str.zfill(width)Return a copy of the string left filled with ASCII >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168077 digits to make a string of length width. A leading sign prefix ( >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168078/ >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168079) is handled by inserting the padding after the sign character rather than before. The original string is returned if width is less than or equal to >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'13. For example: >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'2 def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order) 26-style String FormattingNote The formatting operations described here exhibit a variety of quirks that lead to a number of common errors (such as failing to display tuples and dictionaries correctly). Using the newer , the interface, or may help avoid these errors. Each of these alternatives provides their own trade-offs and benefits of simplicity, flexibility, and/or extensibility. String objects have one unique built-in operation: the >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168083 operator (modulo). This is also known as the string formatting or interpolation operator. Given >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168084 (where format is a string), >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168083 conversion specifications in format are replaced with zero or more elements of values. The effect is similar to using the >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168086 in the C language. If format requires a single argument, values may be a single non-tuple object. Otherwise, values must be a tuple with exactly the number of items specified by the format string, or a single mapping object (for example, a dictionary). A conversion specifier contains two or more characters and has the following components, which must occur in this order:
When the right argument is a dictionary (or other mapping type), then the formats in the string must include a parenthesised mapping key into that dictionary inserted immediately after the >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168087 character. The mapping key selects the value to be formatted from the mapping. For example: >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'3 In this case no >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'00 specifiers may occur in a format (since they require a sequential parameter list). The conversion flag characters are: Flag Meaning >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168094 The value conversion will use the “alternate form” (where defined below). >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168077 The conversion will be zero padded for numeric values. >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168079 The converted value is left adjusted (overrides the >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168077 conversion if both are given). >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168098 (a space) A blank should be left before a positive number (or empty string) produced by a signed conversion. >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168078 A sign character ( >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168078 or >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168079) will precede the conversion (overrides a “space” flag). A length modifier ( def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n02, def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n03, or def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n04) may be present, but is ignored as it is not necessary for Python – so e.g. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n05 is identical to def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n06. The conversion types are: Conversion Meaning Notes def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n07 Signed integer decimal. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n08 Signed integer decimal. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n09 Signed octal value. (1) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n10 Obsolete type – it is identical to def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n07. (6) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n12 Signed hexadecimal (lowercase). (2) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n13 Signed hexadecimal (uppercase). (2) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n14 Floating point exponential format (lowercase). (3) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n15 Floating point exponential format (uppercase). (3) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n16 Floating point decimal format. (3) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n17 Floating point decimal format. (3) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n18 Floating point format. Uses lowercase exponential format if exponent is less than -4 or not less than precision, decimal format otherwise. (4) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n19 Floating point format. Uses uppercase exponential format if exponent is less than -4 or not less than precision, decimal format otherwise. (4) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n20 Single character (accepts integer or single character string). def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n21 String (converts any Python object using ). (5) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n23 String (converts any Python object using ). (5) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n25 String (converts any Python object using ). (5) >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168087 No argument is converted, results in a >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168087 character in the result. Notes:
Since Python strings have an explicit length, def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n36 conversions do not assume that def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n37 is the end of the string. Changed in version 3.1: def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n38 conversions for numbers whose absolute value is over 1e50 are no longer replaced by def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n39 conversions. Binary Sequence Types — , ,The core built-in types for manipulating binary data are and . They are supported by which uses the to access the memory of other binary objects without needing to make a copy. The module supports efficient storage of basic data types like 32-bit integers and IEEE754 double-precision floating values. Bytes ObjectsBytes objects are immutable sequences of single bytes. Since many major binary protocols are based on the ASCII text encoding, bytes objects offer several methods that are only valid when working with ASCII compatible data and are closely related to string objects in a variety of other ways. class bytes([source[, encoding[, errors]]])Firstly, the syntax for bytes literals is largely the same as that for string literals, except that a def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n47 prefix is added:
Only ASCII characters are permitted in bytes literals (regardless of the declared source code encoding). Any binary values over 127 must be entered into bytes literals using the appropriate escape sequence. As with string literals, bytes literals may also use a >>> (65).to_bytes() b'A'62 prefix to disable processing of escape sequences. See for more about the various forms of bytes literal, including supported escape sequences. While bytes literals and representations are based on ASCII text, bytes objects actually behave like immutable sequences of integers, with each value in the sequence restricted such that def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n53 (attempts to violate this restriction will trigger ). This is done deliberately to emphasise that while many binary formats include ASCII based elements and can be usefully manipulated with some text-oriented algorithms, this is not generally the case for arbitrary binary data (blindly applying text processing algorithms to binary data formats that are not ASCII compatible will usually lead to data corruption). In addition to the literal forms, bytes objects can be created in a number of other ways:
Also see the built-in. Since 2 hexadecimal digits correspond precisely to a single byte, hexadecimal numbers are a commonly used format for describing binary data. Accordingly, the bytes type has an additional class method to read data in that format: classmethod fromhex(string)This class method returns a bytes object, decoding the given string object. The string must contain two hexadecimal digits per byte, with ASCII whitespace being ignored. >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'4 Changed in version 3.7: now skips all ASCII whitespace in the string, not just spaces. A reverse conversion function exists to transform a bytes object into its hexadecimal representation. hex([sep[, bytes_per_sep]])Return a string object containing two hexadecimal digits for each byte in the instance. >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'5 If you want to make the hex string easier to read, you can specify a single character separator sep parameter to include in the output. By default, this separator will be included between each byte. A second optional bytes_per_sep parameter controls the spacing. Positive values calculate the separator position from the right, negative values from the left. >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'6 New in version 3.5. Changed in version 3.8: now supports optional sep and bytes_per_sep parameters to insert separators between bytes in the hex output. Since bytes objects are sequences of integers (akin to a tuple), for a bytes object b, def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n61 will be an integer, while def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n62 will be a bytes object of length 1. (This contrasts with text strings, where both indexing and slicing will produce a string of length 1) The representation of bytes objects uses the literal format ( def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n63) since it is often more useful than e.g. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n64. You can always convert a bytes object into a list of integers using def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n65. Bytearray Objectsobjects are a mutable counterpart to objects. class bytearray([source[, encoding[, errors]]])There is no dedicated literal syntax for bytearray objects, instead they are always created by calling the constructor:
As bytearray objects are mutable, they support the sequence operations in addition to the common bytes and bytearray operations described in . Also see the built-in. Since 2 hexadecimal digits correspond precisely to a single byte, hexadecimal numbers are a commonly used format for describing binary data. Accordingly, the bytearray type has an additional class method to read data in that format: classmethod fromhex(string)This class method returns bytearray object, decoding the given string object. The string must contain two hexadecimal digits per byte, with ASCII whitespace being ignored. >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'7 Changed in version 3.7: now skips all ASCII whitespace in the string, not just spaces. A reverse conversion function exists to transform a bytearray object into its hexadecimal representation. hex([sep[, bytes_per_sep]])Return a string object containing two hexadecimal digits for each byte in the instance. >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'8 New in version 3.5. Changed in version 3.8: Similar to , now supports optional sep and bytes_per_sep parameters to insert separators between bytes in the hex output. Since bytearray objects are sequences of integers (akin to a list), for a bytearray object b, def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n61 will be an integer, while def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n62 will be a bytearray object of length 1. (This contrasts with text strings, where both indexing and slicing will produce a string of length 1) The representation of bytearray objects uses the bytes literal format ( def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n78) since it is often more useful than e.g. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n79. You can always convert a bytearray object into a list of integers using def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n65. Bytes and Bytearray OperationsBoth bytes and bytearray objects support the sequence operations. They interoperate not just with operands of the same type, but with any . Due to this flexibility, they can be freely mixed in operations without causing errors. However, the return type of the result may depend on the order of operands. Note The methods on bytes and bytearray objects don’t accept strings as their arguments, just as the methods on strings don’t accept bytes as their arguments. For example, you have to write: >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'9 and: >>> (65).to_bytes() b'A'0 Some bytes and bytearray operations assume the use of ASCII compatible binary formats, and hence should be avoided when working with arbitrary binary data. These restrictions are covered below. Note Using these ASCII based operations to manipulate binary data that is not stored in an ASCII based format may lead to data corruption. The following methods on bytes and bytearray objects can be used with arbitrary binary data. bytes.count(sub[, start[, end]])bytearray.count(sub[, start[, end]])Return the number of non-overlapping occurrences of subsequence sub in the range [start, end]. Optional arguments start and end are interpreted as in slice notation. The subsequence to search for may be any or an integer in the range 0 to 255. If sub is empty, returns the number of empty slices between characters which is the length of the bytes object plus one. Changed in version 3.3: Also accept an integer in the range 0 to 255 as the subsequence. bytes.removeprefix(prefix, /)bytearray.removeprefix(prefix, /)If the binary data starts with the prefix string, return def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n81. Otherwise, return a copy of the original binary data: >>> (65).to_bytes() b'A'1 The prefix may be any . Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. New in version 3.9. bytes.removesuffix(suffix, /)bytearray.removesuffix(suffix, /)If the binary data ends with the suffix string and that suffix is not empty, return def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n82. Otherwise, return a copy of the original binary data: >>> (65).to_bytes() b'A'2 The suffix may be any . Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. New in version 3.9. bytes.decode(encoding='utf-8', errors='strict')bytearray.decode(encoding='utf-8', errors='strict')Return the bytes decoded to a . encoding defaults to def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)36; see for possible values. errors controls how decoding errors are handled. If def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)37 (the default), a exception is raised. Other possible values are def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)39, def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)40, and any other name registered via . See for details. For performance reasons, the value of errors is not checked for validity unless a decoding error actually occurs, is enabled or a is used. Note Passing the encoding argument to allows decoding any directly, without needing to make a temporary >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'23 or >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'24 object. Changed in version 3.1: Added support for keyword arguments. Changed in version 3.9: The value of the errors argument is now checked in and in . bytes.endswith(suffix[, start[, end]])bytearray.endswith(suffix[, start[, end]])Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if the binary data ends with the specified suffix, otherwise return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638. suffix can also be a tuple of suffixes to look for. With optional start, test beginning at that position. With optional end, stop comparing at that position. The suffix(es) to search for may be any . bytes.find(sub[, start[, end]])bytearray.find(sub[, start[, end]])Return the lowest index in the data where the subsequence sub is found, such that sub is contained in the slice def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)49. Optional arguments start and end are interpreted as in slice notation. Return >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 341 if sub is not found. The subsequence to search for may be any or an integer in the range 0 to 255. Note The method should be used only if you need to know the position of sub. To check if sub is a substring or not, use the operator: >>> (65).to_bytes() b'A'3 Changed in version 3.3: Also accept an integer in the range 0 to 255 as the subsequence. bytes.index(sub[, start[, end]])bytearray.index(sub[, start[, end]])Like , but raise when the subsequence is not found. The subsequence to search for may be any or an integer in the range 0 to 255. Changed in version 3.3: Also accept an integer in the range 0 to 255 as the subsequence. bytes.join(iterable)bytearray.join(iterable)Return a bytes or bytearray object which is the concatenation of the binary data sequences in iterable. A will be raised if there are any values in iterable that are not , including objects. The separator between elements is the contents of the bytes or bytearray object providing this method. static bytes.maketrans(from, to)static bytearray.maketrans(from, to)This static method returns a translation table usable for that will map each character in from into the character at the same position in to; from and to must both be and have the same length. New in version 3.1. bytes.partition(sep)bytearray.partition(sep)Split the sequence at the first occurrence of sep, and return a 3-tuple containing the part before the separator, the separator itself or its bytearray copy, and the part after the separator. If the separator is not found, return a 3-tuple containing a copy of the original sequence, followed by two empty bytes or bytearray objects. The separator to search for may be any . bytes.replace(old, new[, count])bytearray.replace(old, new[, count])Return a copy of the sequence with all occurrences of subsequence old replaced by new. If the optional argument count is given, only the first count occurrences are replaced. The subsequence to search for and its replacement may be any . Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.rfind(sub[, start[, end]])bytearray.rfind(sub[, start[, end]])Return the highest index in the sequence where the subsequence sub is found, such that sub is contained within def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)49. Optional arguments start and end are interpreted as in slice notation. Return >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 341 on failure. The subsequence to search for may be any or an integer in the range 0 to 255. Changed in version 3.3: Also accept an integer in the range 0 to 255 as the subsequence. bytes.rindex(sub[, start[, end]])bytearray.rindex(sub[, start[, end]])Like but raises when the subsequence sub is not found. The subsequence to search for may be any or an integer in the range 0 to 255. Changed in version 3.3: Also accept an integer in the range 0 to 255 as the subsequence. bytes.rpartition(sep)bytearray.rpartition(sep)Split the sequence at the last occurrence of sep, and return a 3-tuple containing the part before the separator, the separator itself or its bytearray copy, and the part after the separator. If the separator is not found, return a 3-tuple containing two empty bytes or bytearray objects, followed by a copy of the original sequence. The separator to search for may be any . bytes.startswith(prefix[, start[, end]])bytearray.startswith(prefix[, start[, end]])Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if the binary data starts with the specified prefix, otherwise return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638. prefix can also be a tuple of prefixes to look for. With optional start, test beginning at that position. With optional end, stop comparing at that position. The prefix(es) to search for may be any . bytes.translate(table, /, delete=b'')bytearray.translate(table, /, delete=b'')Return a copy of the bytes or bytearray object where all bytes occurring in the optional argument delete are removed, and the remaining bytes have been mapped through the given translation table, which must be a bytes object of length 256. You can use the method to create a translation table. Set the table argument to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631 for translations that only delete characters: >>> (65).to_bytes() b'A'4 Changed in version 3.6: delete is now supported as a keyword argument. The following methods on bytes and bytearray objects have default behaviours that assume the use of ASCII compatible binary formats, but can still be used with arbitrary binary data by passing appropriate arguments. Note that all of the bytearray methods in this section do not operate in place, and instead produce new objects. bytes.center(width[, fillbyte])bytearray.center(width[, fillbyte])Return a copy of the object centered in a sequence of length width. Padding is done using the specified fillbyte (default is an ASCII space). For objects, the original sequence is returned if width is less than or equal to >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'13. Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.ljust(width[, fillbyte])bytearray.ljust(width[, fillbyte])Return a copy of the object left justified in a sequence of length width. Padding is done using the specified fillbyte (default is an ASCII space). For objects, the original sequence is returned if width is less than or equal to >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'13. Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.lstrip([chars])bytearray.lstrip([chars])Return a copy of the sequence with specified leading bytes removed. The chars argument is a binary sequence specifying the set of byte values to be removed - the name refers to the fact this method is usually used with ASCII characters. If omitted or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, the chars argument defaults to removing ASCII whitespace. The chars argument is not a prefix; rather, all combinations of its values are stripped: >>> (65).to_bytes() b'A'5 The binary sequence of byte values to remove may be any . See for a method that will remove a single prefix string rather than all of a set of characters. For example: >>> (65).to_bytes() b'A'6 Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.rjust(width[, fillbyte])bytearray.rjust(width[, fillbyte])Return a copy of the object right justified in a sequence of length width. Padding is done using the specified fillbyte (default is an ASCII space). For objects, the original sequence is returned if width is less than or equal to >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'13. Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.rsplit(sep=None, maxsplit=- 1)bytearray.rsplit(sep=None, maxsplit=- 1)Split the binary sequence into subsequences of the same type, using sep as the delimiter string. If maxsplit is given, at most maxsplit splits are done, the rightmost ones. If sep is not specified or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, any subsequence consisting solely of ASCII whitespace is a separator. Except for splitting from the right, behaves like which is described in detail below.bytes.rstrip([chars])bytearray.rstrip([chars]) Return a copy of the sequence with specified trailing bytes removed. The chars argument is a binary sequence specifying the set of byte values to be removed - the name refers to the fact this method is usually used with ASCII characters. If omitted or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, the chars argument defaults to removing ASCII whitespace. The chars argument is not a suffix; rather, all combinations of its values are stripped: >>> (65).to_bytes() b'A'7 The binary sequence of byte values to remove may be any . See for a method that will remove a single suffix string rather than all of a set of characters. For example: >>> (65).to_bytes() b'A'8 Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.split(sep=None, maxsplit=- 1)bytearray.split(sep=None, maxsplit=- 1)Split the binary sequence into subsequences of the same type, using sep as the delimiter string. If maxsplit is given and non-negative, at most maxsplit splits are done (thus, the list will have at most >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168037 elements). If maxsplit is not specified or is >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 341, then there is no limit on the number of splits (all possible splits are made). If sep is given, consecutive delimiters are not grouped together and are deemed to delimit empty subsequences (for example, >>> (-2.0).is_integer() True >>> (3.2).is_integer() False27 returns >>> (-2.0).is_integer() True >>> (3.2).is_integer() False28). The sep argument may consist of a multibyte sequence (for example, >>> (-2.0).is_integer() True >>> (3.2).is_integer() False29 returns >>> (-2.0).is_integer() True >>> (3.2).is_integer() False30). Splitting an empty sequence with a specified separator returns >>> (-2.0).is_integer() True >>> (3.2).is_integer() False31 or >>> (-2.0).is_integer() True >>> (3.2).is_integer() False32 depending on the type of object being split. The sep argument may be any . For example: >>> (65).to_bytes() b'A'9 If sep is not specified or is def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, a different splitting algorithm is applied: runs of consecutive ASCII whitespace are regarded as a single separator, and the result will contain no empty strings at the start or end if the sequence has leading or trailing whitespace. Consequently, splitting an empty sequence or a sequence consisting solely of ASCII whitespace without a specified separator returns def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 649. For example: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)0bytes.strip([chars])bytearray.strip([chars]) Return a copy of the sequence with specified leading and trailing bytes removed. The chars argument is a binary sequence specifying the set of byte values to be removed - the name refers to the fact this method is usually used with ASCII characters. If omitted or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, the chars argument defaults to removing ASCII whitespace. The chars argument is not a prefix or suffix; rather, all combinations of its values are stripped: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)1 The binary sequence of byte values to remove may be any . Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. The following methods on bytes and bytearray objects assume the use of ASCII compatible binary formats and should not be applied to arbitrary binary data. Note that all of the bytearray methods in this section do not operate in place, and instead produce new objects. bytes.capitalize()bytearray.capitalize()Return a copy of the sequence with each byte interpreted as an ASCII character, and the first byte capitalized and the rest lowercased. Non-ASCII byte values are passed through unchanged. Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.expandtabs(tabsize=8)bytearray.expandtabs(tabsize=8)Return a copy of the sequence where all ASCII tab characters are replaced by one or more ASCII spaces, depending on the current column and the given tab size. Tab positions occur every tabsize bytes (default is 8, giving tab positions at columns 0, 8, 16 and so on). To expand the sequence, the current column is set to zero and the sequence is examined byte by byte. If the byte is an ASCII tab character ( >>> (-2.0).is_integer() True >>> (3.2).is_integer() False36), one or more space characters are inserted in the result until the current column is equal to the next tab position. (The tab character itself is not copied.) If the current byte is an ASCII newline ( >>> (-2.0).is_integer() True >>> (3.2).is_integer() False37) or carriage return ( >>> (-2.0).is_integer() True >>> (3.2).is_integer() False38), it is copied and the current column is reset to zero. Any other byte value is copied unchanged and the current column is incremented by one regardless of how the byte value is represented when printed: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)2 Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.isalnum()bytearray.isalnum()Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all bytes in the sequence are alphabetical ASCII characters or ASCII decimal digits and the sequence is not empty, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. Alphabetic ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False41. ASCII decimal digits are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False42. For example: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)3bytes.isalpha()bytearray.isalpha() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all bytes in the sequence are alphabetic ASCII characters and the sequence is not empty, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. Alphabetic ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False41. For example: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)4bytes.isascii()bytearray.isascii() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if the sequence is empty or all bytes in the sequence are ASCII, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. ASCII bytes are in the range 0-0x7F. New in version 3.7. bytes.isdigit()bytearray.isdigit()Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all bytes in the sequence are ASCII decimal digits and the sequence is not empty, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. ASCII decimal digits are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False42. For example: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)5bytes.islower()bytearray.islower() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if there is at least one lowercase ASCII character in the sequence and no uppercase ASCII characters, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. For example: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)6 Lowercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False53. Uppercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False54.bytes.isspace()bytearray.isspace() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if all bytes in the sequence are ASCII whitespace and the sequence is not empty, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. ASCII whitespace characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False57 (space, tab, newline, carriage return, vertical tab, form feed).bytes.istitle()bytearray.istitle() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if the sequence is ASCII titlecase and the sequence is not empty, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. See for more details on the definition of “titlecase”. For example: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)7bytes.isupper()bytearray.isupper() Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if there is at least one uppercase alphabetic ASCII character in the sequence and no lowercase ASCII characters, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638 otherwise. For example: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)8 Lowercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False53. Uppercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False54.bytes.lower()bytearray.lower() Return a copy of the sequence with all the uppercase ASCII characters converted to their corresponding lowercase counterpart. For example: def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order)9 Lowercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False53. Uppercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False54. Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.splitlines(keepends=False)bytearray.splitlines(keepends=False)Return a list of the lines in the binary sequence, breaking at ASCII line boundaries. This method uses the approach to splitting lines. Line breaks are not included in the resulting list unless keepends is given and true. For example: >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 167116800 Unlike when a delimiter string sep is given, this method returns an empty list for the empty string, and a terminal line break does not result in an extra line: >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 167116801bytes.swapcase()bytearray.swapcase() Return a copy of the sequence with all the lowercase ASCII characters converted to their corresponding uppercase counterpart and vice-versa. For example: >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 167116802 Lowercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False53. Uppercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False54. Unlike , it is always the case that >>> (-2.0).is_integer() True >>> (3.2).is_integer() False71 for the binary versions. Case conversions are symmetrical in ASCII, even though that is not generally true for arbitrary Unicode code points. Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.title()bytearray.title()Return a titlecased version of the binary sequence where words start with an uppercase ASCII character and the remaining characters are lowercase. Uncased byte values are left unmodified. For example: >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 167116803 Lowercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False53. Uppercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False54. All other byte values are uncased. The algorithm uses a simple language-independent definition of a word as groups of consecutive letters. The definition works in many contexts but it means that apostrophes in contractions and possessives form word boundaries, which may not be the desired result: >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 167116804 A workaround for apostrophes can be constructed using regular expressions: >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 167116805 Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.upper()bytearray.upper()Return a copy of the sequence with all the lowercase ASCII characters converted to their corresponding uppercase counterpart. For example: >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 167116806 Lowercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False53. Uppercase ASCII characters are those byte values in the sequence >>> (-2.0).is_integer() True >>> (3.2).is_integer() False54. Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. bytes.zfill(width)bytearray.zfill(width)Return a copy of the sequence left filled with ASCII >>> (-2.0).is_integer() True >>> (3.2).is_integer() False76 digits to make a sequence of length width. A leading sign prefix ( >>> (-2.0).is_integer() True >>> (3.2).is_integer() False77/ >>> (-2.0).is_integer() True >>> (3.2).is_integer() False78) is handled by inserting the padding after the sign character rather than before. For objects, the original sequence is returned if width is less than or equal to >>> (-2.0).is_integer() True >>> (3.2).is_integer() False80. For example: >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 167116807 Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. def to_bytes(n, length=1, byteorder='big', signed=False): if byteorder == 'little': order = range(length) elif byteorder == 'big': order = reversed(range(length)) else: raise ValueError("byteorder must be either 'little' or 'big'") return bytes((n >> i*8) & 0xff for i in order) 26-style Bytes FormattingNote The formatting operations described here exhibit a variety of quirks that lead to a number of common errors (such as failing to display tuples and dictionaries correctly). If the value being printed may be a tuple or dictionary, wrap it in a tuple. Bytes objects ( >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'23/ >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'24) have one unique built-in operation: the >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168083 operator (modulo). This is also known as the bytes formatting or interpolation operator. Given >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168084 (where format is a bytes object), >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168083 conversion specifications in format are replaced with zero or more elements of values. The effect is similar to using the >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168086 in the C language. If format requires a single argument, values may be a single non-tuple object. Otherwise, values must be a tuple with exactly the number of items specified by the format bytes object, or a single mapping object (for example, a dictionary). A conversion specifier contains two or more characters and has the following components, which must occur in this order:
When the right argument is a dictionary (or other mapping type), then the formats in the bytes object must include a parenthesised mapping key into that dictionary inserted immediately after the >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168087 character. The mapping key selects the value to be formatted from the mapping. For example: >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 167116808 In this case no >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'00 specifiers may occur in a format (since they require a sequential parameter list). The conversion flag characters are: Flag Meaning >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168094 The value conversion will use the “alternate form” (where defined below). >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168077 The conversion will be zero padded for numeric values. >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168079 The converted value is left adjusted (overrides the >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168077 conversion if both are given). >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168098 (a space) A blank should be left before a positive number (or empty string) produced by a signed conversion. >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168078 A sign character ( >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168078 or >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168079) will precede the conversion (overrides a “space” flag). A length modifier ( def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n02, def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n03, or def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n04) may be present, but is ignored as it is not necessary for Python – so e.g. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n05 is identical to def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n06. The conversion types are: Conversion Meaning Notes def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n07 Signed integer decimal. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n08 Signed integer decimal. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n09 Signed octal value. (1) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n10 Obsolete type – it is identical to def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n07. (8) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n12 Signed hexadecimal (lowercase). (2) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n13 Signed hexadecimal (uppercase). (2) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n14 Floating point exponential format (lowercase). (3) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n15 Floating point exponential format (uppercase). (3) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n16 Floating point decimal format. (3) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n17 Floating point decimal format. (3) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n18 Floating point format. Uses lowercase exponential format if exponent is less than -4 or not less than precision, decimal format otherwise. (4) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n19 Floating point format. Uses uppercase exponential format if exponent is less than -4 or not less than precision, decimal format otherwise. (4) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n20 Single byte (accepts integer or single byte objects). def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6022 Bytes (any object that follows the or has def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6023). (5) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n23 def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n23 is an alias for def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6022 and should only be used for Python2/3 code bases. (6) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n25 Bytes (converts any Python object using def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6028). (5) def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n21 def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n21 is an alias for def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n25 and should only be used for Python2/3 code bases. (7) >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168087 No argument is converted, results in a >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 1671168087 character in the result. Notes:
Note The bytearray version of this method does not operate in place - it always produces a new object, even if no changes were made. See also PEP 461 - Adding % formatting to bytes and bytearray New in version 3.5. Memory Viewsobjects allow Python code to access the internal data of an object that supports the without copying. class memoryview(object)Create a that references object. object must support the buffer protocol. Built-in objects that support the buffer protocol include and . A has the notion of an element, which is the atomic memory unit handled by the originating object. For many simple types such as and , an element is a single byte, but other types such as may have bigger elements. def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6051 is equal to the length of . If def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6053, the length is 1. If def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6054, the length is equal to the number of elements in the view. For higher dimensions, the length is equal to the length of the nested list representation of the view. The attribute will give you the number of bytes in a single element. A supports slicing and indexing to expose its data. One-dimensional slicing will result in a subview: >>> int.from_bytes(b'\x00\x10', byteorder='big') 16 >>> int.from_bytes(b'\x00\x10', byteorder='little') 4096 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=True) -1024 >>> int.from_bytes(b'\xfc\x00', byteorder='big', signed=False) 64512 >>> int.from_bytes([255, 0, 0], byteorder='big') 167116809 If is one of the native format specifiers from the module, indexing with an integer or a tuple of integers is also supported and returns a single element with the correct type. One-dimensional memoryviews can be indexed with an integer or a one-integer tuple. Multi-dimensional memoryviews can be indexed with tuples of exactly ndim integers where ndim is the number of dimensions. Zero-dimensional memoryviews can be indexed with the empty tuple. Here is an example with a non-byte format: def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n0 If the underlying object is writable, the memoryview supports one-dimensional slice assignment. Resizing is not allowed: def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n1 One-dimensional memoryviews of hashable (read-only) types with formats ‘B’, ‘b’ or ‘c’ are also hashable. The hash is defined as def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6059: def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n2 Changed in version 3.3: One-dimensional memoryviews can now be sliced. One-dimensional memoryviews with formats ‘B’, ‘b’ or ‘c’ are now hashable. Changed in version 3.4: memoryview is now registered automatically with Changed in version 3.5: memoryviews can now be indexed with tuple of integers. has several methods: __eq__(exporter)A memoryview and a PEP 3118 exporter are equal if their shapes are equivalent and if all corresponding values are equal when the operands’ respective format codes are interpreted using syntax. For the subset of format strings currently supported by , def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6065 and def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6066 are equal if def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6067: def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n3 If either format string is not supported by the module, then the objects will always compare as unequal (even if the format strings and buffer contents are identical): def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n4 Note that, as with floating point numbers, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6069 does not imply def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6070 for memoryview objects. Changed in version 3.3: Previous versions compared the raw memory disregarding the item format and the logical array structure. tobytes(order='C')Return the data in the buffer as a bytestring. This is equivalent to calling the constructor on the memoryview. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n5 For non-contiguous arrays the result is equal to the flattened list representation with all elements converted to bytes. supports all format strings, including those that are not in module syntax. New in version 3.8: order can be {‘C’, ‘F’, ‘A’}. When order is ‘C’ or ‘F’, the data of the original array is converted to C or Fortran order. For contiguous views, ‘A’ returns an exact copy of the physical memory. In particular, in-memory Fortran order is preserved. For non-contiguous views, the data is converted to C first. order=None is the same as order=’C’. hex([sep[, bytes_per_sep]])Return a string object containing two hexadecimal digits for each byte in the buffer. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n6 New in version 3.5. Changed in version 3.8: Similar to , now supports optional sep and bytes_per_sep parameters to insert separators between bytes in the hex output. tolist()Return the data in the buffer as a list of elements. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n7 Changed in version 3.3: now supports all single character native formats in module syntax as well as multi-dimensional representations. toreadonly()Return a readonly version of the memoryview object. The original memoryview object is unchanged. def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n8 New in version 3.8. release()Release the underlying buffer exposed by the memoryview object. Many objects take special actions when a view is held on them (for example, a would temporarily forbid resizing); therefore, calling release() is handy to remove these restrictions (and free any dangling resources) as soon as possible. After this method has been called, any further operation on the view raises a (except itself which can be called multiple times): def from_bytes(bytes, byteorder='big', signed=False): if byteorder == 'little': little_ordered = list(bytes) elif byteorder == 'big': little_ordered = list(reversed(bytes)) else: raise ValueError("byteorder must be either 'little' or 'big'") n = sum(b << i*8 for i, b in enumerate(little_ordered)) if signed and little_ordered and (little_ordered[-1] & 0x80): n -= 1 << 8*len(little_ordered) return n9 The context management protocol can be used for a similar effect, using the def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6081 statement: >>> (-2.0).is_integer() True >>> (3.2).is_integer() False0 New in version 3.2. cast(format[, shape])Cast a memoryview to a new format or shape. shape defaults to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6082, which means that the result view will be one-dimensional. The return value is a new memoryview, but the buffer itself is not copied. Supported casts are 1D -> C- and C-contiguous -> 1D. The destination format is restricted to a single element native format in syntax. One of the formats must be a byte format (‘B’, ‘b’ or ‘c’). The byte length of the result must be the same as the original length. Cast 1D/long to 1D/unsigned bytes: >>> (-2.0).is_integer() True >>> (3.2).is_integer() False1 Cast 1D/unsigned bytes to 1D/char: >>> (-2.0).is_integer() True >>> (3.2).is_integer() False2 Cast 1D/bytes to 3D/ints to 1D/signed char: >>> (-2.0).is_integer() True >>> (3.2).is_integer() False3 Cast 1D/unsigned long to 2D/unsigned long: >>> (-2.0).is_integer() True >>> (3.2).is_integer() False4 New in version 3.3. Changed in version 3.5: The source format is no longer restricted when casting to a byte view. There are also several readonly attributes available: objThe underlying object of the memoryview: >>> (-2.0).is_integer() True >>> (3.2).is_integer() False5 New in version 3.3. nbytesdef bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6084. This is the amount of space in bytes that the array would use in a contiguous representation. It is not necessarily equal to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6085: >>> (-2.0).is_integer() True >>> (3.2).is_integer() False6 Multi-dimensional arrays: >>> (-2.0).is_integer() True >>> (3.2).is_integer() False7 New in version 3.3. readonlyA bool indicating whether the memory is read only. formatA string containing the format (in module style) for each element in the view. A memoryview can be created from exporters with arbitrary format strings, but some methods (e.g. ) are restricted to native single element formats. Changed in version 3.3: format def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6088 is now handled according to the struct module syntax. This means that def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6089.itemsize The size in bytes of each element of the memoryview: >>> (-2.0).is_integer() True >>> (3.2).is_integer() False8ndim An integer indicating how many dimensions of a multi-dimensional array the memory represents. shapeA tuple of integers the length of giving the shape of the memory as an N-dimensional array. Changed in version 3.3: An empty tuple instead of def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631 when ndim = 0.strides A tuple of integers the length of giving the size in bytes to access each element for each dimension of the array. Changed in version 3.3: An empty tuple instead of def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631 when ndim = 0.suboffsets Used internally for PIL-style arrays. The value is informational only. c_contiguousA bool indicating whether the memory is C-. New in version 3.3. f_contiguousA bool indicating whether the memory is Fortran . New in version 3.3. contiguousA bool indicating whether the memory is . New in version 3.3. Set Types — ,A set object is an unordered collection of distinct objects. Common uses include membership testing, removing duplicates from a sequence, and computing mathematical operations such as intersection, union, difference, and symmetric difference. (For other containers see the built-in , , and classes, and the module.) Like other collections, sets support def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6100, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6101, and def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6102. Being an unordered collection, sets do not record element position or order of insertion. Accordingly, sets do not support indexing, slicing, or other sequence-like behavior. There are currently two built-in set types, and . The type is mutable — the contents can be changed using methods like def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6106 and >>> (65).to_bytes() b'A'01. Since it is mutable, it has no hash value and cannot be used as either a dictionary key or as an element of another set. The type is immutable and — its contents cannot be altered after it is created; it can therefore be used as a dictionary key or as an element of another set. Non-empty sets (not frozensets) can be created by placing a comma-separated list of elements within braces, for example: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6109, in addition to the constructor. The constructors for both classes work the same: class set([iterable])class frozenset([iterable])Return a new set or frozenset object whose elements are taken from iterable. The elements of a set must be . To represent sets of sets, the inner sets must be objects. If iterable is not specified, a new empty set is returned. Sets can be created by several means:
Instances of and provide the following operations: len(s)Return the number of elements in set s (cardinality of s). x in sTest x for membership in s. x not in sTest x for non-membership in s. isdisjoint(other)Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if the set has no elements in common with other. Sets are disjoint if and only if their intersection is the empty set.issubset(other)set <= other Test whether every element in the set is in other. set < otherTest whether the set is a proper subset of other, that is, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6120.issuperset(other)set >= other Test whether every element in other is in the set. set > otherTest whether the set is a proper superset of other, that is, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6121.union(*others)set | other | ... Return a new set with elements from the set and all others. intersection(*others)set & other & ...Return a new set with elements common to the set and all others. difference(*others)set - other - ...Return a new set with elements in the set that are not in the others. symmetric_difference(other)set ^ otherReturn a new set with elements in either the set or other but not both. copy()Return a shallow copy of the set. Note, the non-operator versions of , , , , , and methods will accept any iterable as an argument. In contrast, their operator based counterparts require their arguments to be sets. This precludes error-prone constructions like def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6128 in favor of the more readable def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6129. Both and support set to set comparisons. Two sets are equal if and only if every element of each set is contained in the other (each is a subset of the other). A set is less than another set if and only if the first set is a proper subset of the second set (is a subset, but is not equal). A set is greater than another set if and only if the first set is a proper superset of the second set (is a superset, but is not equal). Instances of are compared to instances of based on their members. For example, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6134 returns def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 and so does def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6136. The subset and equality comparisons do not generalize to a total ordering function. For example, any two nonempty disjoint sets are not equal and are not subsets of each other, so all of the following return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6138, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6139, or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6140. Since sets only define partial ordering (subset relationships), the output of the method is undefined for lists of sets. Set elements, like dictionary keys, must be . Binary operations that mix instances with return the type of the first operand. For example: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6144 returns an instance of . The following table lists operations available for that do not apply to immutable instances of : update(*others)set |= other | ...Update the set, adding elements from all others. intersection_update(*others)set &= other & ...Update the set, keeping only elements found in it and all others. difference_update(*others)set -= other | ...Update the set, removing elements found in others. symmetric_difference_update(other)set ^= otherUpdate the set, keeping only elements found in either set, but not in both. add(elem)Add element elem to the set. remove(elem)Remove element elem from the set. Raises if elem is not contained in the set. discard(elem)Remove element elem from the set if it is present. pop()Remove and return an arbitrary element from the set. Raises if the set is empty. clear()Remove all elements from the set. Note, the non-operator versions of the , , , and methods will accept any iterable as an argument. Note, the elem argument to the >>> n = 19 >>> bin(n) '0b10011' >>> n.bit_count() 3 >>> (-n).bit_count() 300, , and methods may be a set. To support searching for an equivalent frozenset, a temporary one is created from elem. Mapping Types —A object maps values to arbitrary objects. Mappings are mutable objects. There is currently only one standard mapping type, the dictionary. (For other containers see the built-in , , and classes, and the module.) A dictionary’s keys are almost arbitrary values. Values that are not , that is, values containing lists, dictionaries or other mutable types (that are compared by value rather than by object identity) may not be used as keys. Values that compare equal (such as def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 655, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6163, and def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656) can be used interchangeably to index the same dictionary entry.class dict(**kwargs)class dict(mapping, **kwargs)class dict(iterable, **kwargs) Return a new dictionary initialized from an optional positional argument and a possibly empty set of keyword arguments. Dictionaries can be created by several means:
If no positional argument is given, an empty dictionary is created. If a positional argument is given and it is a mapping object, a dictionary is created with the same key-value pairs as the mapping object. Otherwise, the positional argument must be an object. Each item in the iterable must itself be an iterable with exactly two objects. The first object of each item becomes a key in the new dictionary, and the second object the corresponding value. If a key occurs more than once, the last value for that key becomes the corresponding value in the new dictionary. If keyword arguments are given, the keyword arguments and their values are added to the dictionary created from the positional argument. If a key being added is already present, the value from the keyword argument replaces the value from the positional argument. To illustrate, the following examples all return a dictionary equal to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6173: >>> (-2.0).is_integer() True >>> (3.2).is_integer() False9 Providing keyword arguments as in the first example only works for keys that are valid Python identifiers. Otherwise, any valid keys can be used. These are the operations that dictionaries support (and therefore, custom mapping types should support too): list(d)Return a list of all the keys used in the dictionary d. len(d)Return the number of items in the dictionary d. d[key]Return the item of d with key key. Raises a if key is not in the map. If a subclass of dict defines a method def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6175 and key is not present, the def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6176 operation calls that method with the key key as argument. The def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6176 operation then returns or raises whatever is returned or raised by the def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6178 call. No other operations or methods invoke def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6175. If def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6175 is not defined, is raised. def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6175 must be a method; it cannot be an instance variable: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 600 The example above shows part of the implementation of . A different def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6184 method is used by .d[key] = value Set def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6176 to value.del d[key] Remove def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6176 from d. Raises a if key is not in the map.key in d Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if d has a key key, else def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638.key not in d Equivalent to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6191.iter(d) Return an iterator over the keys of the dictionary. This is a shortcut for def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6192.clear() Remove all items from the dictionary. copy()Return a shallow copy of the dictionary. classmethod fromkeys(iterable[, value])Create a new dictionary with keys from iterable and values set to value. is a class method that returns a new dictionary. value defaults to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631. All of the values refer to just a single instance, so it generally doesn’t make sense for value to be a mutable object such as an empty list. To get distinct values, use a instead.get(key[, default]) Return the value for key if key is in the dictionary, else default. If default is not given, it defaults to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631, so that this method never raises a .items() Return a new view of the dictionary’s items ( def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6197 pairs). See the .keys() Return a new view of the dictionary’s keys. See the . pop(key[, default])If key is in the dictionary, remove it and return its value, else return default. If default is not given and key is not in the dictionary, a is raised. popitem()Remove and return a def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6197 pair from the dictionary. Pairs are returned in LIFO order. is useful to destructively iterate over a dictionary, as often used in set algorithms. If the dictionary is empty, calling raises a . Changed in version 3.7: LIFO order is now guaranteed. In prior versions, would return an arbitrary key/value pair. reversed(d)Return a reverse iterator over the keys of the dictionary. This is a shortcut for def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6204. New in version 3.8. setdefault(key[, default])If key is in the dictionary, return its value. If not, insert key with a value of default and return default. default defaults to def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631.update([other]) Update the dictionary with the key/value pairs from other, overwriting existing keys. Return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631. accepts either another dictionary object or an iterable of key/value pairs (as tuples or other iterables of length two). If keyword arguments are specified, the dictionary is then updated with those key/value pairs: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6208.values() Return a new view of the dictionary’s values. See the . An equality comparison between one def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6209 view and another will always return def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 638. This also applies when comparing def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6209 to itself: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 601d | other Create a new dictionary with the merged keys and values of d and other, which must both be dictionaries. The values of other take priority when d and other share keys. New in version 3.9. d |= otherUpdate the dictionary d with keys and values from other, which may be either a or an of key/value pairs. The values of other take priority when d and other share keys. New in version 3.9. Dictionaries compare equal if and only if they have the same def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6197 pairs (regardless of ordering). Order comparisons (‘<’, ‘<=’, ‘>=’, ‘>’) raise . Dictionaries preserve insertion order. Note that updating a key does not affect the order. Keys added after deletion are inserted at the end. def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 602 Changed in version 3.7: Dictionary order is guaranteed to be insertion order. This behavior was an implementation detail of CPython from 3.6. Dictionaries and dictionary views are reversible. def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 603 Changed in version 3.8: Dictionaries are now reversible. See also can be used to create a read-only view of a . Dictionary view objectsThe objects returned by , and are view objects. They provide a dynamic view on the dictionary’s entries, which means that when the dictionary changes, the view reflects these changes. Dictionary views can be iterated over to yield their respective data, and support membership tests: len(dictview)Return the number of entries in the dictionary. iter(dictview)Return an iterator over the keys, values or items (represented as tuples of def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6197) in the dictionary. Keys and values are iterated over in insertion order. This allows the creation of def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6220 pairs using : def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6222. Another way to create the same list is def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6223. Iterating views while adding or deleting entries in the dictionary may raise a or fail to iterate over all entries. Changed in version 3.7: Dictionary order is guaranteed to be insertion order. x in dictviewReturn def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 656 if x is in the underlying dictionary’s keys, values or items (in the latter case, x should be a def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6197 tuple).reversed(dictview) Return a reverse iterator over the keys, values or items of the dictionary. The view will be iterated in reverse order of the insertion. Changed in version 3.8: Dictionary views are now reversible. dictview.mappingReturn a that wraps the original dictionary to which the view refers. New in version 3.10. Keys views are set-like since their entries are unique and hashable. If all values are hashable, so that def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6197 pairs are unique and hashable, then the items view is also set-like. (Values views are not treated as set-like since the entries are generally not unique.) For set-like views, all of the operations defined for the abstract base class are available (for example, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 678, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 674, or def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6232). An example of dictionary view usage: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 604 Context Manager TypesPython’s statement supports the concept of a runtime context defined by a context manager. This is implemented using a pair of methods that allow user-defined classes to define a runtime context that is entered before the statement body is executed and exited when the statement ends: contextmanager.__enter__()Enter the runtime context and return either this object or another object related to the runtime context. The value returned by this method is bound to the identifier in the def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6234 clause of statements using this context manager. An example of a context manager that returns itself is a . File objects return themselves from __enter__() to allow to be used as the context expression in a statement. An example of a context manager that returns a related object is the one returned by . These managers set the active decimal context to a copy of the original decimal context and then return the copy. This allows changes to be made to the current decimal context in the body of the statement without affecting code outside the def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6081 statement.contextmanager.__exit__(exc_type, exc_val, exc_tb) Exit the runtime context and return a Boolean flag indicating if any exception that occurred should be suppressed. If an exception occurred while executing the body of the statement, the arguments contain the exception type, value and traceback information. Otherwise, all three arguments are def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 631. Returning a true value from this method will cause the statement to suppress the exception and continue execution with the statement immediately following the def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6081 statement. Otherwise the exception continues propagating after this method has finished executing. Exceptions that occur during execution of this method will replace any exception that occurred in the body of the def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6081 statement. The exception passed in should never be reraised explicitly - instead, this method should return a false value to indicate that the method completed successfully and does not want to suppress the raised exception. This allows context management code to easily detect whether or not an method has actually failed. Python defines several context managers to support easy thread synchronisation, prompt closure of files or other objects, and simpler manipulation of the active decimal arithmetic context. The specific types are not treated specially beyond their implementation of the context management protocol. See the module for some examples. Python’s s and the decorator provide a convenient way to implement these protocols. If a generator function is decorated with the decorator, it will return a context manager implementing the necessary and methods, rather than the iterator produced by an undecorated generator function. Note that there is no specific slot for any of these methods in the type structure for Python objects in the Python/C API. Extension types wanting to define these methods must provide them as a normal Python accessible method. Compared to the overhead of setting up the runtime context, the overhead of a single class dictionary lookup is negligible. Type Annotation Types — ,The core built-in types for are and . Generic Alias Typedef bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6252 objects are generally created by a class. They are most often used with , such as or . For example, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6255 is a def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6252 object created by subscripting the def bit_count(self): return bin(self).count("1")93 class with the argument . def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6252 objects are intended primarily for use with . Note It is generally only possible to subscript a class if the class implements the special method . A def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6252 object acts as a proxy for a , implementing parameterized generics. For a container class, the argument(s) supplied to a of the class may indicate the type(s) of the elements an object contains. For example, def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6262 can be used in type annotations to signify a in which all the elements are of type . For a class which defines but is not a container, the argument(s) supplied to a subscription of the class will often indicate the return type(s) of one or more methods defined on an object. For example, can be used on both the data type and the data type:
def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6252 objects are instances of the class , which can also be used to create def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6252 objects directly.T[X, Y, ...] Creates a def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6252 representing a type def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6289 parameterized by types X, Y, and more depending on the def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6289 used. For example, a function expecting a containing elements: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 605 Another example for objects, using a , which is a generic type expecting two type parameters representing the key type and the value type. In this example, the function expects a >>> (1024).to_bytes(2, byteorder='big') b'\x04\x00' >>> (1024).to_bytes(10, byteorder='big') b'\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00' >>> (-1024).to_bytes(10, byteorder='big', signed=True) b'\xff\xff\xff\xff\xff\xff\xff\xff\xfc\x00' >>> x = 1000 >>> x.to_bytes((x.bit_length() + 7) // 8, byteorder='little') b'\xe8\x03'68 with keys of type and values of type : def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 606 The builtin functions and do not accept def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6252 types for their second argument: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 607 The Python runtime does not enforce . This extends to generic types and their type parameters. When creating a container object from a def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6252, the elements in the container are not checked against their type. For example, the following code is discouraged, but will run without errors: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 608 Furthermore, parameterized generics erase type parameters during object creation: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 609 Calling or on a generic shows the parameterized type: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 610 The method of generic containers will raise an exception to disallow mistakes like def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6304: def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 611 However, such expressions are valid when are used. The index must have as many elements as there are type variable items in the def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 6252 object’s . def bit_length(self): s = bin(self) # binary representation: bin(-37) --> '-0b100101' s = s.lstrip('-0b') # remove leading zeros and minus sign return len(s) # len('100101') --> 612 Standard Generic ClassesThe following standard library classes support parameterized generics. This list is non-exhaustive. Special Attributes of |
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