Python Built in Functions Flashcards
abs(x)
abs(x)
Return the absolute value of a number. The argument may be an integer or a floating point number. If the argument is a complex number, its magnitude is returned. If x defines __abs__(), abs(x) returns x.__abs__().
all(iterable)
all(iterable)
Return True if all elements of the iterable are true (or if the iterable is empty). Equivalent to:
def all(iterable):
for element in iterable:
if not element:
return False
return True
any(iterable)
any(iterable)
Return True if any element of the iterable is true. If the iterable is empty, return False. Equivalent to:
def any(iterable):
for element in iterable:
if element:
return True
return False
ascii(object)
ascii(object) As repr(), return a string containing a printable representation of an object, but escape the non-ASCII characters in the string returned by repr() using \x, \u or \U escapes. This generates a string similar to that returned by repr() in Python 2.
bin(x)
bin(x)
Convert an integer number to a binary string prefixed with “0b”. The result is a valid Python expression. If x is not a Python int object, it has to define an __index__() method that returns an integer. Some examples:
> > > bin(3)
‘0b11’
bin(-10)
‘-0b1010’
f prefix “0b” is desired or not, you can use either of the following ways.
>>>format(14, '#b'), format(14, 'b')
('0b1110', '1110')
>>>f'{14:#b}', f'{14:b}'
('0b1110', '1110')
class bool([x])
class bool([x]) Return a Boolean value, i.e. one of True or False. x is converted using the standard truth testing procedure. If x is false or omitted, this returns False; otherwise it returns True. The bool class is a subclass of int (see Numeric Types — int, float, complex). It cannot be subclassed further. Its only instances are False and True (see Boolean Values).
breakpoint(*args, *kws)
breakpoint(*args, **kws)
This function drops you into the debugger at the call site. Specifically, it calls sys.breakpointhook(), passing args and kws straight through. By default, sys.breakpointhook() calls pdb.set_trace() expecting no arguments. In this case, it is purely a convenience function so you don’t have to explicitly import pdb or type as much code to enter the debugger. However, sys.breakpointhook() can be set to some other function and breakpoint() will automatically call that, allowing you to drop into the debugger of choice.
Raises an auditing event builtins.breakpoint with argument breakpointhook.
class bytearray([source[, encoding[, errors]]])
class bytearray([source[, encoding[, errors]]]) Return a new array of bytes. The bytearray class is a mutable sequence of integers in the range 0 <= x < 256. It has most of the usual methods of mutable sequences, described in Mutable Sequence Types, as well as most methods that the bytes type has, see Bytes and Bytearray Operations.
The optional source parameter can be used to initialize the array in a few different ways:
If it is a string, you must also give the encoding (and optionally, errors) parameters; bytearray() then converts the string to bytes using str.encode().
If it is an integer, the array will have that size and will be initialized with null bytes.
If it is an object conforming to the buffer interface, a read-only buffer of the object will be used to initialize the bytes array.
If it is an iterable, it must be an iterable of integers in the range 0 <= x < 256, which are used as the initial contents of the array.
Without an argument, an array of size 0 is created.
See also Binary Sequence Types — bytes, bytearray, memoryview and Bytearray Objects.
class bytes([source[, encoding[, errors]]])
class bytes([source[, encoding[, errors]]]) Return a new “bytes” object, which is an immutable sequence of integers in the range 0 <= x < 256. bytes is an immutable version of bytearray – it has the same non-mutating methods and the same indexing and slicing behavior.
Accordingly, constructor arguments are interpreted as for bytearray().
Bytes objects can also be created with literals, see String and Bytes literals.
See also Binary Sequence Types — bytes, bytearray, memoryview, Bytes Objects, and Bytes and Bytearray Operations.
callable(object)
callable(object) Return True if the object argument appears callable, False if not. If this returns True, it is still possible that a call fails, but if it is False, calling object will never succeed. Note that classes are callable (calling a class returns a new instance); instances are callable if their class has a \_\_call\_\_() method.
chr(i)
chr(i)
Return the string representing a character whose Unicode code point is the integer i. For example, chr(97) returns the string ‘a’, while chr(8364) returns the string ‘€’. This is the inverse of ord().
The valid range for the argument is from 0 through 1,114,111 (0x10FFFF in base 16). ValueError will be raised if i is outside that range.
@classmethod
@classmethod Transform a method into a class method.
A class method receives the class as implicit first argument, just like an instance method receives the instance. To declare a class method, use this idiom:
class C:
@classmethod
def f(cls, arg1, arg2, ...): ...
The @classmethod form is a function decorator – see Function definitions for details.
A class method can be called either on the class (such as C.f()) or on an instance (such as C().f()). The instance is ignored except for its class. If a class method is called for a derived class, the derived class object is passed as the implied first argument.
Class methods are different than C++ or Java static methods. If you want those, see staticmethod().
For more information on class methods, see The standard type hierarchy.
compile(source, filename, mode, flags=0, dont_inherit=False, optimize=-1)
compile(source, filename, mode, flags=0, dont_inherit=False, optimize=-1) Compile the source into a code or AST object. Code objects can be executed by exec() or eval(). source can either be a normal string, a byte string, or an AST object. Refer to the ast module documentation for information on how to work with AST objects.
The filename argument should
class complex([real[, imag]])
class complex([real[, imag]]) Return a complex number with the value real + imag*1j or convert a string or number to a complex number. If the first parameter is a string, it will be interpreted as a complex number and the function must be called without a second parameter. The second parameter can never be a string. Each argument may be any numeric type (including complex). If imag is omitted, it defaults to zero and the constructor serves as a numeric conversion like int and float. If both arguments are omitted, returns 0j.
For a general Python o
delattr(object, name)
delattr(object, name)
This is a relative of setattr(). The arguments are an object and a string. The string must be the name of one of the object’s attributes. The function deletes the named attribute, provided the object allows it. For example, delattr(x, ‘foobar’) is equivalent to del x.foobar.
dir([object])
dir([object])
Without arguments, return the list of names in the current local scope. With an argument, attempt to return a list of valid attributes for that object.
If the object has a method named _
divmod(a, b)
divmod(a, b) Take two (non complex) numbers as arguments and return a pair of numbers consisting of their quotient and remainder when using integer division. With mixed operand types, the rules for binary arithmetic operators apply. For integers, the result is the same as (a // b, a % b). For floating point numbers the result is (q, a % b), where q is usually math.floor(a / b) but may be 1 less than that. In any case q * b + a % b is very close to a, if a % b is non-zero it has the same sign as b, and 0 <= abs(a % b) < abs(b).
enumerate(iterable, start=0)
enumerate(iterable, start=0)
Return an enumerate object. iterable must be a sequence, an iterator, or some other object which supports iteration. The __next__() method of the iterator returned by enumerate() returns a tuple containing a count (from start which defaults to 0) and the values obtained from iterating over iterable.
> > > seasons = [‘Spring’, ‘Summer’, ‘Fall’, ‘Winter’]
list(enumerate(seasons))
[(0, ‘Spring’), (1, ‘Summer’), (2, ‘Fall’), (3, ‘Winter’)]
list(enumerate(seasons, start=1))
[(1, ‘Spring’), (2, ‘Summer’), (3, ‘Fall’), (4, ‘Winter’)]
Equivalent to:
def enumerate(sequence, start=0):
n = start
for elem in sequence:
yield n, elem
n += 1
eval(expression[, globals[, locals]])
eval(expression[, globals[, locals]])
The arguments are a string and optional globals and locals. If provided, globals must be a dictionary. If provided, locals can be any mapping object.
The expression argument is parsed
exec(object[, globals[, locals]])
exec(object[, globals[, locals]])
This function supports dynamic execution of Python code. object must be either a string or a code object. If it is a string, the string is parsed as a suite of Python statements which is then executed (unless a syntax error occurs). 1 If it is a code object, it is simply executed. In all cases, the code that’s executed is expected to be valid as file input (see the section “File input” in the Reference Manual). Be aware that the nonlocal, yield, and return statements may not be used outside of function definitions even within the context of code passed to the exec() function. The return value is None.
In all cases, if the optional parts are omitted,
filter(function, iterable)
filter(function, iterable)
Construct an iterator from those elements of iterable for which function returns true. iterable may be either a sequence, a container which supports iteration, or an iterator. If function is None, the identity function is assumed, that is, all elements of iterable that are false are removed.
Note that filter(function, iterable) is equivalent to the generator expression (item for item in iterable if function(item)) if function is not None and (item for item in iterable if item) if function is None.
See itertools.filterfalse() for the complementary function that returns elements of iterable for which function returns false.
class float([x])
class float([x]) Return a floating point number constructed from a number or string x.
If the argument is a string, it should
format(value[, format_spec])
format(value[, format_spec])
Convert a value to a “formatted” representation, as controlled by format_spec. The interpretation of format_spec will depend on the type of the value argument, however there is a standard formatting syntax that is used by most built-in types: Format Specification Mini-Language.
The default format_spec is an
class frozenset([iterable])
class frozenset([iterable]) Return a new frozenset object, optionally with elements taken from iterable. frozenset is a built-in class. See frozenset and Set Types — set, frozenset for documentation about this class.
For other containers see the built-in set, list, tuple, and dict classes, as well as the collections module.
getattr(object, name[, default])
getattr(object, name[, default])
Return the value of the named attribute of object. name must be a string. If the string is the name of one of the object’s attributes, the result is the value of that attribute. For example, getattr(x, ‘foobar’) is equivalent to x.foobar. If the named attribute does not exist, default is returned if provided, otherwise AttributeError is raised.
globals()
globals() Return a dictionary representing the current global symbol table. This is always the dictionary of the current module (inside a function or method, this is the module where it is defined, not the module from which it is called).
hasattr(object, name)
hasattr(object, name)
The arguments are an object and a string. The result is True if the string is the name of one of the object’s attributes, False if not. (This is implemented by calling getattr(object, name) and seeing whether it raises an AttributeError or not.)
