2. Funções Built-in¶

The Python interpreter has a number of functions built into it that are always available. They are listed here in alphabetical order.

		Funções Built-in
`abs()`	`divmod()`	`input()`	`open()`	`staticmethod()`
`all()`	`enumerate()`	`int()`	`ord()`	`str()`
`any()`	`eval()`	`isinstance()`	`pow()`	`sum()`
`basestring()`	`execfile()`	`issubclass()`	`print()`	`super()`
`bin()`	`file()`	`iter()`	`property()`	`tuple()`
`bool()`	`filter()`	`len()`	`range()`	`type()`
`bytearray()`	`float()`	`list()`	`raw_input()`	`unichr()`
`callable()`	`format()`	`locals()`	`reduce()`	`unicode()`
`chr()`	`frozenset()`	`long()`	`reload()`	`vars()`
`classmethod()`	`getattr()`	`map()`	`repr()`	`xrange()`
`cmp()`	`globals()`	`max()`	`reversed()`	`zip()`
`compile()`	`hasattr()`	`memoryview()`	`round()`	`__import__()`
`complex()`	`hash()`	`min()`	`set()`
`delattr()`	`help()`	`next()`	`setattr()`
`dict()`	`hex()`	`object()`	`slice()`
`dir()`	`id()`	`oct()`	`sorted()`

In addition, there are other four built-in functions that are no longer considered essential: apply(), buffer(), coerce(), and intern(). They are documented in the Non-essential Built-in Functions section.

abs(x)¶: Return the absolute value of a number. The argument may be a plain or long integer or a floating point number. If the argument is a complex number, its magnitude is returned.

all(iterable)¶

Retorna True se todos os elementos de iterable são verdadeiros (ou se iterable estiver vazio). Equivalente a:

def all(iterable):
    for element in iterable:
        if not element:
            return False
    return True

Novo na versão 2.5.

any(iterable)¶

Retorna True se qualquer elemento de iterable for verdadeiros. Se iterable estiver vazio, retorna False. Equivalente a:

def any(iterable):
    for element in iterable:
        if element:
            return True
    return False

Novo na versão 2.5.

basestring()¶: This abstract type is the superclass for str and unicode. It cannot be called or instantiated, but it can be used to test whether an object is an instance of str or unicode. isinstance(obj, basestring) is equivalent to isinstance(obj, (str, unicode)).

Novo na versão 2.3.

bin(x)¶: Converte um número inteiro para uma string binária. O resultado é uma expressão Python válida. Se x não é um objeto Python int, ele tem que definir um método __index__() que retorna um inteiro.

Novo na versão 2.6.

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. bool is also a class, which is a subclass of int. Class bool cannot be subclassed further. Its only instances are False and True.

Novo na versão 2.2.1.

Alterado na versão 2.3: If no argument is given, this function returns False.

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 Tipos de Sequências Mutáveis, as well as most methods that the str type has, see Métodos de String.

O parãmetro opcional source pode ser usado para inicializar o vetor de algumas maneiras diferentes:

If it is unicode, you must also give the encoding (and optionally, errors) parameters; bytearray() then converts the unicode to bytes using unicode.encode().
Se é um integer, o array terá esse tamanho e será inicializado com bytes nulos.
Se é um objeto em conformidade com a interface buffer, um buffer de objeto somente leitura será usado para inicializar o vetor de bytes.
Se é um iterável, deve ser um iterável de inteiros no intervalo 0 <= x < 256, que serão usados como o conteúdo inicial do vetor.

Sem argumentos, um vetor de tamanho 0 é criado.

Novo na versão 2.6.

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); class instances are callable if they have a __call__() method.

chr(i)¶: Return a string of one character whose ASCII code is the integer i. For example, chr(97) returns the string 'a'. This is the inverse of ord(). The argument must be in the range [0..255], inclusive; ValueError will be raised if i is outside that range. See also unichr().

classmethod(function)¶

Return a class method for function.

Um método de classe recebe a classe como primeiro argumento implícito, exatamente como uma método de instância recebe a instância. Para declarar um método de classe, faça dessa forma:

class C(object):
    @classmethod
    def f(cls, arg1, arg2, ...):
        ...

O termo @classmethod é uma função decorator – veja Function definitions para detalhes.

Um método de classe pode ser chamado tanto da classe (como em C.f()) quanto da instância (como em C().f()). A instância é ignorada, exceto por sua classe. Se um método de classe é chamado por uma classe derivada, o objeto da classe derivada é passado como primeiro argumento implícito.

Métodos de classe são diferentes de métodos estáticos em C++ ou Java. Se você quer saber desses, veja staticmethod().

Para mais informações sobre métodos de classe, veja A hierarquia de tipos padrão.

Novo na versão 2.2.

Alterado na versão 2.4: Function decorator syntax added.

cmp(x, y)¶: Compare the two objects x and y and return an integer according to the outcome. The return value is negative if x < y, zero if x == y and strictly positive if x > y.

compile(source, filename, mode[, flags[, dont_inherit]])¶

Compile the source into a code or AST object. Code objects can be executed by an exec statement or evaluated by a call to eval(). source can either be a Unicode string, a Latin-1 encoded string or an AST object. Refer to the ast module documentation for information on how to work with AST objects.

O argumento filename deve ser o arquivo de onde o código será lido; passe algum valor reconhecível se isso não foi lido de um arquivo ('<string>' é comumente usado).

O argumento mode especifica qual o tipo de código deve ser compilado; pode ser 'exec' se source consiste de uma sequência de instruções, 'eval' se consiste de uma única expressão, ou 'single' se consiste de uma única instrução interativa (neste último caso, instruções que são avaliadas para alguma coisa diferente de None serão exibidas).

The optional arguments flags and dont_inherit control which future statements (see PEP 236) affect the compilation of source. If neither is present (or both are zero) the code is compiled with those future statements that are in effect in the code that is calling compile(). If the flags argument is given and dont_inherit is not (or is zero) then the future statements specified by the flags argument are used in addition to those that would be used anyway. If dont_inherit is a non-zero integer then the flags argument is it – the future statements in effect around the call to compile are ignored.

Instruções futuras são especificadas por bits, assim pode ocorrer uma operação OU bit a bit para especificar múltiplas instruções. O sinalizador necessário para especificar um dado recurso pode ser encontrada no atributo compiler_flag na instância _Feature do módulo __future__ module.

This function raises SyntaxError if the compiled source is invalid, and TypeError if the source contains null bytes.

Se você quer analisar código Python em sua representação AST, veja ast.parse().

Nota

Quando compilindo uma string com código multi-linhas em modo 'single' ou 'eval', entrada deve ser terminada por ao menos um caractere de nova linhas. Isso é para facilitar a detecção de instruções completas e incompletas no módulo code.

Aviso

É possível quebrar o interpretador Python com uma string suficiente grande/complexa quando compilando para uma objeto AST, devido limitações do tamanho da pilha no compilador AST do Python.

Alterado na versão 2.3: The flags and dont_inherit arguments were added.

Alterado na versão 2.6: Support for compiling AST objects.

Alterado na versão 2.7: Allowed use of Windows and Mac newlines. Also input in 'exec' mode does not have to end in a newline anymore.

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 function serves as a numeric conversion function like int(), long() and float(). If both arguments are omitted, returns 0j.

Nota

Quando convertendo a partir de uma string, a string não pode conter espaços em branco em torno + central ou do operador -. Por exemplo, complex('1+2j') funciona, mas complex('1 + 2j') levanta ValueError.

O tipo complexo está descrito em Numeric Types — int, float, long, complex.

delattr(object, name)¶: Essa função está relacionada com setattr(). Os argumentos são um objeto e uma string. A string deve ser o nome de um dos atributos do objeto. A função remove o atributo indicado, desde que o objeto permita. Por exemplo, delattr(x, 'foobar') é equivalente a del x.foobar.

class dict(**kwarg)

class dict(mapping, **kwarg)

class dict(iterable, **kwarg)

Cria um novo dicionário. O objeto dict é a classe do dicionário. Veja dict e Tipo de Mapeamento — dict para documentação sobre esta classe.

Para outros contêineres, consulte as classes internas list, set e tuple, bem como o módulo collections.

dir([object])¶

Sem argumentos, retorne a lista de nomes no escopo local atual. Com um argumento, tente retornar uma lista de atributos válidos para esse objeto.

Se o objeto tiver um método chamado __dir__(), esse método será chamado e deve retornar a lista de atributos. Isso permite que objetos que implementam uma função personalizada __getattr__() ou __getattribute__() personalizem a maneira dir() relata seus atributos.

Se o objeto não fornecer __dir__(), a função tentará o melhor possível para coletar informações do atributo __dict__ do objeto, se definido, e do seu objeto de tipo. A lista resultante não está necessariamente completa e pode ser imprecisa quando o objeto possui um __getattr__() personalizado.

O mecanismo padrão dir() se comporta de maneira diferente com diferentes tipos de objetos, pois tenta produzir as informações mais relevantes e não completas:

Se o objeto for um objeto de módulo, a lista conterá os nomes dos atributos do módulo.
Se o objeto for um objeto de tipo ou classe, a lista conterá os nomes de seus atributos e recursivamente os atributos de suas bases.
Caso contrário, a lista conterá os nomes dos atributos do objeto, os nomes dos atributos da classe e recursivamente os atributos das classes base da classe.

A lista resultante é alfabeticamente ordenada. Por exemplo:

>>> import struct
>>> dir()   # show the names in the module namespace
['__builtins__', '__doc__', '__name__', 'struct']
>>> dir(struct)   # show the names in the struct module
['Struct', '__builtins__', '__doc__', '__file__', '__name__',
 '__package__', '_clearcache', 'calcsize', 'error', 'pack', 'pack_into',
 'unpack', 'unpack_from']
>>> class Shape(object):
        def __dir__(self):
            return ['area', 'perimeter', 'location']
>>> s = Shape()
>>> dir(s)
['area', 'perimeter', 'location']

Nota

Como dir() é fornecido principalmente como uma conveniência para uso em um prompt interativo, ele tenta fornecer um conjunto interessante de nomes mais do que tenta fornecer um conjunto de nomes definido de forma rigorosa ou consistente, e seu comportamento detalhado pode mudar nos lançamentos. Por exemplo, os atributos de metaclasse não estão na lista de resultados quando o argumento é uma classe.

divmod(a, b)¶: Take two (non complex) numbers as arguments and return a pair of numbers consisting of their quotient and remainder when using long division. With mixed operand types, the rules for binary arithmetic operators apply. For plain and long 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).

Alterado na versão 2.3: Using divmod() with complex numbers is deprecated.

enumerate(sequence, start=0)¶

Return an enumerate object. sequence 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 sequence:

>>> 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')]

Equivalente a:

def enumerate(sequence, start=0):
    n = start
    for elem in sequence:
        yield n, elem
        n += 1

Novo na versão 2.3.

Alterado na versão 2.6: The start parameter was added.

eval(expression[, globals[, locals]])¶

The arguments are a Unicode or Latin-1 encoded string and optional globals and locals. If provided, globals must be a dictionary. If provided, locals can be any mapping object.

Alterado na versão 2.4: formerly locals was required to be a dictionary.

The expression argument is parsed and evaluated as a Python expression (technically speaking, a condition list) using the globals and locals dictionaries as global and local namespace. If the globals dictionary is present and lacks ‘__builtins__’, the current globals are copied into globals before expression is parsed. This means that expression normally has full access to the standard __builtin__ module and restricted environments are propagated. If the locals dictionary is omitted it defaults to the globals dictionary. If both dictionaries are omitted, the expression is executed in the environment where eval() is called. The return value is the result of the evaluated expression. Syntax errors are reported as exceptions. Example:

>>> x = 1
>>> print eval('x+1')
2

Esta função também pode ser usada para executar objetos de código arbitrários (como os criados por compile()). Nesse caso, passe um objeto de código em vez de uma string. Se o objeto de código foi compilado com 'exec' como o argumento mode, o valor de retorno de eval() será` None`.

Hints: dynamic execution of statements is supported by the exec statement. Execution of statements from a file is supported by the execfile() function. The globals() and locals() functions returns the current global and local dictionary, respectively, which may be useful to pass around for use by eval() or execfile().

Veja ast.literal_eval() para uma função que pode avaliar com segurança strings com expressões contendo apenas literais.

execfile(filename[, globals[, locals]])¶

This function is similar to the exec statement, but parses a file instead of a string. It is different from the import statement in that it does not use the module administration — it reads the file unconditionally and does not create a new module. 1

The arguments are a file name and two optional dictionaries. The file is parsed and evaluated as a sequence of Python statements (similarly to a module) using the globals and locals dictionaries as global and local namespace. If provided, locals can be any mapping object. Remember that at module level, globals and locals are the same dictionary. If two separate objects are passed as globals and locals, the code will be executed as if it were embedded in a class definition.

Alterado na versão 2.4: formerly locals was required to be a dictionary.

If the locals dictionary is omitted it defaults to the globals dictionary. If both dictionaries are omitted, the expression is executed in the environment where execfile() is called. The return value is None.

Nota

The default locals act as described for function locals() below: modifications to the default locals dictionary should not be attempted. Pass an explicit locals dictionary if you need to see effects of the code on locals after function execfile() returns. execfile() cannot be used reliably to modify a function’s locals.

file(name[, mode[, buffering]])¶

Constructor function for the file type, described further in section Objetos File. The constructor’s arguments are the same as those of the open() built-in function described below.

When opening a file, it’s preferable to use open() instead of invoking this constructor directly. file is more suited to type testing (for example, writing isinstance(f, file)).

Novo na versão 2.2.

filter(function, iterable)¶

Construct a list 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 iterable is a string or a tuple, the result also has that type; otherwise it is always a list. 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 [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.ifilter() and itertools.ifilterfalse() for iterator versions of this function, including a variation that filters for elements where the function returns false.

class float([x])¶

Retorna um número de ponto flutuante construído a partir de um número ou string * x *.

If the argument is a string, it must contain a possibly signed decimal or floating point number, possibly embedded in whitespace. The argument may also be [+|-]nan or [+|-]inf. Otherwise, the argument may be a plain or long integer or a floating point number, and a floating point number with the same value (within Python’s floating point precision) is returned. If no argument is given, returns 0.0.

Nota

When passing in a string, values for NaN and Infinity may be returned, depending on the underlying C library. Float accepts the strings nan, inf and -inf for NaN and positive or negative infinity. The case and a leading + are ignored as well as a leading - is ignored for NaN. Float always represents NaN and infinity as nan, inf or -inf.

O tipo float é descrito em Numeric Types — int, float, long, complex.

format(value[, format_spec])¶: Converte um valor value em uma representação “formatada”, como controlado por format_spec. A interpretação de format_spec dependerá do tipo do argumento value, no entanto, há uma sintaxe de formatação padrão usada pela maioria dos tipos embutidos: formspecpec.

Nota

format(value, format_spec) merely calls value.__format__(format_spec).

Novo na versão 2.6.

class frozenset([iterable])

Devolve um novo objeto frozenset, opcionalmente com elementos obtidos de iterable. frozenset é uma classe embutida. Veja frozenset e Tipo Set — set, frozenset para documentação sobre essas classes.

Para outros containers veja as classes embutidas set, list, tuple, e dict, bem como o módulo collections.

Novo na versão 2.4.

getattr(object, name[, default])¶: Devolve o valor do atributo name de object. name deve ser uma string. Se a string é o nome de um dos atributos do objeto, o resultado é o valor de tal atributo. Por exempleo, getattr(x, 'foobar') é equivalente a x.foobar. Se o atributo não existir, default é devolvido se tiver sido fornecido, caso contrário é levantada a exceção AttributeError.

globals()¶: Devolve um dicionário representando a tabela de símbolos global atual. É sempre o dicionário do módulo atual (dentro de uma função ou método, é o módulo onde está definido, não o módulo do qual é chamado).

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 exception or not.)

hash(object)¶: Return the hash value of the object (if it has one). Hash values are integers. They are used to quickly compare dictionary keys during a dictionary lookup. Numeric values that compare equal have the same hash value (even if they are of different types, as is the case for 1 and 1.0).

help([object])¶

Invoca o sistema de ajuda embutido. (Esta função é destinada para uso interativo.) Se nenhum argumento é passado, o sistema interativo de ajuda inicia no interpretador do console. Se o argumento é uma string, então a string é pesquisada como o nome de um módulo, função, classe, metódo, palavra-chave, ou tópico de documentação, e a página de ajuda é exibida no console. Se o argumento é qualquer outro tipo de objeto, uma página de ajuda para o objeto é gerada.

Esta função é adicionada ao espaço de nomes embutido pelo módulo site.

Novo na versão 2.2.

hex(x)¶

Convert an integer number (of any size) to a lowercase hexadecimal string prefixed with “0x”, for example:

>>> hex(255)
'0xff'
>>> hex(-42)
'-0x2a'
>>> hex(1L)
'0x1L'

If x is not a Python int or long object, it has to define a __hex__() method that returns a string.

Veja também int() para converter uma string hexadecimal para um inteiro usando a base 16.

Nota

Para obter uma string hexadecimal de um ponto flutuante, use o método float.hex().

Alterado na versão 2.4: Formerly only returned an unsigned literal.

id(object)¶: Return the “identity” of an object. This is an integer (or long integer) which is guaranteed to be unique and constant for this object during its lifetime. Two objects with non-overlapping lifetimes may have the same id() value.

CPython implementation detail: This is the address of the object in memory.

input([prompt])¶

Equivalent to eval(raw_input(prompt)).

This function does not catch user errors. If the input is not syntactically valid, a SyntaxError will be raised. Other exceptions may be raised if there is an error during evaluation.

Se o módulo readline foi carregado, então input() usará ele para prover edição de linhas elaboradas e funcionalidades de histórico.

Consider using the raw_input() function for general input from users.

class int(x=0)¶

class int(x, base=10)

Return an integer object constructed from a number or string x, or return 0 if no arguments are given. If x is a number, it can be a plain integer, a long integer, or a floating point number. If x is floating point, the conversion truncates towards zero. If the argument is outside the integer range, the function returns a long object instead.

If x is not a number or if base is given, then x must be a string or Unicode object representing an integer literal in radix base. Optionally, the literal can be preceded by + or - (with no space in between) and surrounded by whitespace. A base-n literal consists of the digits 0 to n-1, with a to z (or A to Z) having values 10 to 35. The default base is 10. The allowed values are 0 and 2–36. Base-2, -8, and -16 literals can be optionally prefixed with 0b/0B, 0o/0O/0, or 0x/0X, as with integer literals in code. Base 0 means to interpret the string exactly as an integer literal, so that the actual base is 2, 8, 10, or 16.

O tipo inteiro é descrito em Numeric Types — int, float, long, complex.

isinstance(object, classinfo)¶: Return true if the object argument is an instance of the classinfo argument, or of a (direct, indirect or virtual) subclass thereof. Also return true if classinfo is a type object (new-style class) and object is an object of that type or of a (direct, indirect or virtual) subclass thereof. If object is not a class instance or an object of the given type, the function always returns false. If classinfo is a tuple of class or type objects (or recursively, other such tuples), return true if object is an instance of any of the classes or types. If classinfo is not a class, type, or tuple of classes, types, and such tuples, a TypeError exception is raised.

Alterado na versão 2.2: Support for a tuple of type information was added.

issubclass(class, classinfo)¶: Return true if class is a subclass (direct, indirect or virtual) of classinfo. A class is considered a subclass of itself. classinfo may be a tuple of class objects, in which case every entry in classinfo will be checked. In any other case, a TypeError exception is raised.

Alterado na versão 2.3: Support for a tuple of type information was added.

iter(o[, sentinel])¶

Return an iterator object. The first argument is interpreted very differently depending on the presence of the second argument. Without a second argument, o must be a collection object which supports the iteration protocol (the __iter__() method), or it must support the sequence protocol (the __getitem__() method with integer arguments starting at 0). If it does not support either of those protocols, TypeError is raised. If the second argument, sentinel, is given, then o must be a callable object. The iterator created in this case will call o with no arguments for each call to its next() method; if the value returned is equal to sentinel, StopIteration will be raised, otherwise the value will be returned.

One useful application of the second form of iter() is to read lines of a file until a certain line is reached. The following example reads a file until the readline() method returns an empty string:

with open('mydata.txt') as fp:
    for line in iter(fp.readline, ''):
        process_line(line)

Novo na versão 2.2.

len(s)¶: Retorna o comprimento (o número de itens) de um objeto. O argumento pode ser uma sequência (tal como uma string, bytes, tupla, lista, ou range) ou uma coleção (tal como um dicionário, conjunto, ou conjunto imutável).

class list([iterable])

Return 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 iterable[:]. For instance, list('abc') returns ['a', 'b', 'c'] and list( (1, 2, 3) ) returns [1, 2, 3]. If no argument is given, returns a new empty list, [].

list is a mutable sequence type, as documented in Sequence Types — str, unicode, list, tuple, bytearray, buffer, xrange. For other containers see the built in dict, set, and tuple classes, and the collections module.

locals()¶: Update and return a dictionary representing the current local symbol table. Free variables are returned by locals() when it is called in function blocks, but not in class blocks.

Nota

O conteúdo deste dicionário não deve ser modificado; As alterações podem não afetar os valores das variáveis locais e livres usadas pelo intérprete.

class long(x=0)¶

class long(x, base=10)

Return a long integer object constructed from a string or number x. If the argument is a string, it must contain a possibly signed number of arbitrary size, possibly embedded in whitespace. The base argument is interpreted in the same way as for int(), and may only be given when x is a string. Otherwise, the argument may be a plain or long integer or a floating point number, and a long integer with the same value is returned. Conversion of floating point numbers to integers truncates (towards zero). If no arguments are given, returns 0L.

The long type is described in Numeric Types — int, float, long, complex.

map(function, iterable, ...)¶: Apply function to every item of iterable and return a list of the results. If additional iterable arguments are passed, function must take that many arguments and is applied to the items from all iterables in parallel. If one iterable is shorter than another it is assumed to be extended with None items. If function is None, the identity function is assumed; if there are multiple arguments, map() returns a list consisting of tuples containing the corresponding items from all iterables (a kind of transpose operation). The iterable arguments may be a sequence or any iterable object; the result is always a list.

max(iterable[, key])¶

max(arg1, arg2, *args[, key])

Retorna o maior item em um iterável ou o maior de dois ou mais argumentos.

If one positional argument is provided, iterable must be a non-empty iterable (such as a non-empty string, tuple or list). The largest item in the iterable is returned. If two or more positional arguments are provided, the largest of the positional arguments is returned.

The optional key argument specifies a one-argument ordering function like that used for list.sort(). The key argument, if supplied, must be in keyword form (for example, max(a,b,c,key=func)).

Alterado na versão 2.5: Added support for the optional key argument.

memoryview(obj): Retorna um objeto de “visão da memória” criado a partir do argumento fornecido. Veja memoryview type para mais informações.

min(iterable[, key])¶

min(arg1, arg2, *args[, key])

Retorna o menor item de um iterável ou o menor de dois ou mais argumentos.

If one positional argument is provided, iterable must be a non-empty iterable (such as a non-empty string, tuple or list). The smallest item in the iterable is returned. If two or more positional arguments are provided, the smallest of the positional arguments is returned.

The optional key argument specifies a one-argument ordering function like that used for list.sort(). The key argument, if supplied, must be in keyword form (for example, min(a,b,c,key=func)).

Alterado na versão 2.5: Added support for the optional key argument.

next(iterator[, default])¶: Retrieve the next item from the iterator by calling its next() method. If default is given, it is returned if the iterator is exhausted, otherwise StopIteration is raised.

Novo na versão 2.6.

class object¶: Return a new featureless object. object is a base for all new style classes. It has the methods that are common to all instances of new style classes.

Novo na versão 2.2.

Alterado na versão 2.3: This function does not accept any arguments. Formerly, it accepted arguments but ignored them.

oct(x)¶: Convert an integer number (of any size) to an octal string. The result is a valid Python expression.

Alterado na versão 2.4: Formerly only returned an unsigned literal.

open(name[, mode[, buffering]])¶

Open a file, returning an object of the file type described in section Objetos File. If the file cannot be opened, IOError is raised. When opening a file, it’s preferable to use open() instead of invoking the file constructor directly.

The first two arguments are the same as for stdio’s fopen(): name is the file name to be opened, and mode is a string indicating how the file is to be opened.

The most commonly-used values of mode are 'r' for reading, 'w' for writing (truncating the file if it already exists), and 'a' for appending (which on some Unix systems means that all writes append to the end of the file regardless of the current seek position). If mode is omitted, it defaults to 'r'. The default is to use text mode, which may convert '\n' characters to a platform-specific representation on writing and back on reading. Thus, when opening a binary file, you should append 'b' to the mode value to open the file in binary mode, which will improve portability. (Appending 'b' is useful even on systems that don’t treat binary and text files differently, where it serves as documentation.) See below for more possible values of mode.

The optional buffering argument specifies the file’s desired buffer size: 0 means unbuffered, 1 means line buffered, any other positive value means use a buffer of (approximately) that size (in bytes). A negative buffering means to use the system default, which is usually line buffered for tty devices and fully buffered for other files. If omitted, the system default is used. 2

Modes 'r+', 'w+' and 'a+' open the file for updating (reading and writing); note that 'w+' truncates the file. Append 'b' to the mode to open the file in binary mode, on systems that differentiate between binary and text files; on systems that don’t have this distinction, adding the 'b' has no effect.

In addition to the standard fopen() values mode may be 'U' or 'rU'. Python is usually built with universal newlines support; supplying 'U' opens the file as a text file, but lines may be terminated by any of the following: the Unix end-of-line convention '\n', the Macintosh convention '\r', or the Windows convention '\r\n'. All of these external representations are seen as '\n' by the Python program. If Python is built without universal newlines support a mode with 'U' is the same as normal text mode. Note that file objects so opened also have an attribute called newlines which has a value of None (if no newlines have yet been seen), '\n', '\r', '\r\n', or a tuple containing all the newline types seen.

Python enforces that the mode, after stripping 'U', begins with 'r', 'w' or 'a'.

Python provides many file handling modules including fileinput, os, os.path, tempfile, and shutil.

Alterado na versão 2.5: Restriction on first letter of mode string introduced.

ord(c)¶: Given a string of length one, return an integer representing the Unicode code point of the character when the argument is a unicode object, or the value of the byte when the argument is an 8-bit string. For example, ord('a') returns the integer 97, ord(u'\u2020') returns 8224. This is the inverse of chr() for 8-bit strings and of unichr() for unicode objects. If a unicode argument is given and Python was built with UCS2 Unicode, then the character’s code point must be in the range [0..65535] inclusive; otherwise the string length is two, and a TypeError will be raised.

pow(x, y[, z])¶

Return x to the power y; if z is present, return x to the power y, modulo z (computed more efficiently than pow(x, y) % z). The two-argument form pow(x, y) is equivalent to using the power operator: x**y.

The arguments must have numeric types. With mixed operand types, the coercion rules for binary arithmetic operators apply. For int and long int operands, the result has the same type as the operands (after coercion) unless the second argument is negative; in that case, all arguments are converted to float and a float result is delivered. For example, 10**2 returns 100, but 10**-2 returns 0.01. (This last feature was added in Python 2.2. In Python 2.1 and before, if both arguments were of integer types and the second argument was negative, an exception was raised.) If the second argument is negative, the third argument must be omitted. If z is present, x and y must be of integer types, and y must be non-negative. (This restriction was added in Python 2.2. In Python 2.1 and before, floating 3-argument pow() returned platform-dependent results depending on floating-point rounding accidents.)

print(*objects, sep=' ', end='\n', file=sys.stdout)¶

Print objects to the stream file, separated by sep and followed by end. sep, end and file, if present, must be given as keyword arguments.

Todos os argumentos que não são nomeados são convertidos em strings como str() faz e gravados no fluxo, separados por sep e seguidos por end. sep e end devem ser strings; eles também podem ser None, o que significa usar os valores padrão. Se nenhum object for fornecido, print() escreverá apenas end.

The file argument must be an object with a write(string) method; if it is not present or None, sys.stdout will be used. Output buffering is determined by file. Use file.flush() to ensure, for instance, immediate appearance on a screen.

Nota

This function is not normally available as a built-in since the name print is recognized as the print statement. To disable the statement and use the print() function, use this future statement at the top of your module:

from __future__ import print_function

Novo na versão 2.6.

class property([fget[, fset[, fdel[, doc]]]])¶

Return a property attribute for new-style classes (classes that derive from object).

fget é uma função para obter o valor de um atributo. fset é uma função para definir um valor para um atributo. fdel é uma função para deletar um valor de um atributo. E doc cria um docstring para um atributo.

Um uso comum é para definir um atributo gerenciável x:

class C(object):
    def __init__(self):
        self._x = None

    def getx(self):
        return self._x

    def setx(self, value):
        self._x = value

    def delx(self):
        del self._x

    x = property(getx, setx, delx, "I'm the 'x' property.")

Se c é uma instância de C, c.x irá invocar o método getter, c.x = value irá invocar o método setter, e del c.x o médodo deleter.

Se fornecido, doc será a docstring do atributo property attribute. Otherwise, the property will copy fget’s docstring (if it exists). This makes it possible to create read-only properties easily using property() as a decorator:

class Parrot(object):
    def __init__(self):
        self._voltage = 100000

    @property
    def voltage(self):
        """Get the current voltage."""
        return self._voltage

O decorador @property transforma o método voltage() em um “getter” para um atributo somente leitura com o mesmo nome, e define a docstring de voltage para “Get the current voltage.”

Um objeto property possui métodos getter, setter, e deleter usáveis como decoradores, que criam uma cópia da property com o assessor correspondente a função definida para a função com decorador. Isso é explicado melhor com um exemplo:

class C(object):
    def __init__(self):
        self._x = None

    @property
    def x(self):
        """I'm the 'x' property."""
        return self._x

    @x.setter
    def x(self, value):
        self._x = value

    @x.deleter
    def x(self):
        del self._x

Esse código é exatamente equivalente ao primeiro exemplo. Tenha certeza de nas funções adicionais usar o mesmo nome que a property original (x neste caso).

O objeto property retornado também tem os atributos fget, fset, e fdel correspondendo aos argumentos do construtor.

Novo na versão 2.2.

Alterado na versão 2.5: Use fget’s docstring if no doc given.

Alterado na versão 2.6: The getter, setter, and deleter attributes were added.

range(stop)¶

range(start, stop[, step])

This is a versatile function to create lists containing arithmetic progressions. It is most often used in for loops. The arguments must be plain integers. If the step argument is omitted, it defaults to 1. If the start argument is omitted, it defaults to 0. The full form returns a list of plain integers [start, start + step, start + 2 * step, ...]. If step is positive, the last element is the largest start + i * step less than stop; if step is negative, the last element is the smallest start + i * step greater than stop. step must not be zero (or else ValueError is raised). Example:

>>> range(10)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> range(1, 11)
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>>> range(0, 30, 5)
[0, 5, 10, 15, 20, 25]
>>> range(0, 10, 3)
[0, 3, 6, 9]
>>> range(0, -10, -1)
[0, -1, -2, -3, -4, -5, -6, -7, -8, -9]
>>> range(0)
[]
>>> range(1, 0)
[]

raw_input([prompt])¶

If the prompt argument is present, it is written to standard output without a trailing newline. The function then reads a line from input, converts it to a string (stripping a trailing newline), and returns that. When EOF is read, EOFError is raised. Example:

>>> s = raw_input('--> ')
--> Monty Python's Flying Circus
>>> s
"Monty Python's Flying Circus"

If the readline module was loaded, then raw_input() will use it to provide elaborate line editing and history features.

reduce(function, iterable[, initializer])¶

Apply function of two arguments cumulatively to the items of iterable, from left to right, so as to reduce the iterable to a single value. For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) calculates ((((1+2)+3)+4)+5). The left argument, x, is the accumulated value and the right argument, y, is the update value from the iterable. If the optional initializer is present, it is placed before the items of the iterable in the calculation, and serves as a default when the iterable is empty. If initializer is not given and iterable contains only one item, the first item is returned. Roughly equivalent to:

def reduce(function, iterable, initializer=None):
    it = iter(iterable)
    if initializer is None:
        try:
            initializer = next(it)
        except StopIteration:
            raise TypeError('reduce() of empty sequence with no initial value')
    accum_value = initializer
    for x in it:
        accum_value = function(accum_value, x)
    return accum_value

reload(module)¶

Reload a previously imported module. The argument must be a module object, so it must have been successfully imported before. This is useful if you have edited the module source file using an external editor and want to try out the new version without leaving the Python interpreter. The return value is the module object (the same as the module argument).

When reload(module) is executed:

Python modules’ code is recompiled and the module-level code reexecuted, defining a new set of objects which are bound to names in the module’s dictionary. The init function of extension modules is not called a second time.
As with all other objects in Python the old objects are only reclaimed after their reference counts drop to zero.
The names in the module namespace are updated to point to any new or changed objects.
Other references to the old objects (such as names external to the module) are not rebound to refer to the new objects and must be updated in each namespace where they occur if that is desired.

There are a number of other caveats:

When a module is reloaded, its dictionary (containing the module’s global variables) is retained. Redefinitions of names will override the old definitions, so this is generally not a problem. If the new version of a module does not define a name that was defined by the old version, the old definition remains. This feature can be used to the module’s advantage if it maintains a global table or cache of objects — with a try statement it can test for the table’s presence and skip its initialization if desired:

try:
    cache
except NameError:
    cache = {}

It is generally not very useful to reload built-in or dynamically loaded modules. Reloading sys, __main__, builtins and other key modules is not recommended. In many cases extension modules are not designed to be initialized more than once, and may fail in arbitrary ways when reloaded.

If a module imports objects from another module using from … import …, calling reload() for the other module does not redefine the objects imported from it — one way around this is to re-execute the from statement, another is to use import and qualified names (module.*name*) instead.

If a module instantiates instances of a class, reloading the module that defines the class does not affect the method definitions of the instances — they continue to use the old class definition. The same is true for derived classes.

repr(object)¶: Return a string containing a printable representation of an object. This is the same value yielded by conversions (reverse quotes). It is sometimes useful to be able to access this operation as an ordinary function. For many types, this function makes an attempt to return a string that would yield an object with the same value when passed to eval(), otherwise the representation is a string enclosed in angle brackets that contains the name of the type of the object together with additional information often including the name and address of the object. A class can control what this function returns for its instances by defining a __repr__() method.

reversed(seq)¶: Retorna um iterador reverso. seq deve ser um objeto que possui o método __reversed__() ou suporta o protocolo de sequência (o método __len__() e o método __len__() e o método __getitem__() com argumentos inteiros começando em 0).

Novo na versão 2.4.

Alterado na versão 2.6: Added the possibility to write a custom __reversed__() method.

round(number[, ndigits])¶: Return the floating point value number rounded to ndigits digits after the decimal point. If ndigits is omitted, it defaults to zero. The result is a floating point number. Values are rounded to the closest multiple of 10 to the power minus ndigits; if two multiples are equally close, rounding is done away from 0 (so, for example, round(0.5) is 1.0 and round(-0.5) is -1.0).

Nota

O comportamento de round() para pontos flutuantes pode ser surpreendente: por exemplo, round(2.675, 2) fornece 2.67 em vez do esperado 2.68. Isso não é um bug: é resultado do fato de que a maioria das frações decimais não pode ser representada exatamente como um ponto flutuante. Veja Aritmética de ponto flutuante: problemas e limitações para mais informações.

class set([iterable])

Retorna um novo objeto set, opcionalmente com elementos retirados de iterable. set é uma classe embutida. Veja set e Tipo Set — set, frozenset para documentação sobre esta classe.

Para outros contêineres, consulte as classes embutidas frozenset, list, tuple e dict, bem como o módulo collections.

Novo na versão 2.4.

setattr(object, name, value)¶: Esta é a contrapartida de getattr(). Os argumentos são um objeto, uma string e um valor arbitrário. A string pode nomear um atributo existente ou um novo atributo. A função atribui o valor ao atributo, desde que o objeto permita. Por exemplo, setattr(x, 'foobar', 123) é equivalente a x.foobar = 123.

class slice(stop)¶
class slice(start, stop[, step]): Retorna um objeto slice representando o conjunto de índices especificado por range(start, stop, step). Os argumentos start e step são padronizados como None. Os objetos de têm atributos de dados somente leitura start, stop e step, que meramente retornam os valores do argumento (ou o padrão). Eles não têm outra funcionalidade explícita; no entanto, eles são usados pelo Python numérico e outras extensões de terceiros. Os objetos slice também são gerados quando a sintaxe de indexação estendida é usada. Por exemplo: a[start:stop:step] ou a[start:stop, i]. Veja itertools.islice() para uma versão alternativa que retorna um iterador.

sorted(iterable[, cmp[, key[, reverse]]])¶

Retorna uma nova lista classificada dos itens em iterable.

The optional arguments cmp, key, and reverse have the same meaning as those for the list.sort() method (described in section Tipos de Sequências Mutáveis).

cmp specifies a custom comparison function of two arguments (iterable elements) which should return a negative, zero or positive number depending on whether the first argument is considered smaller than, equal to, or larger than the second argument: cmp=lambda x,y: cmp(x.lower(), y.lower()). The default value is None.

key specifies a function of one argument that is used to extract a comparison key from each list element: key=str.lower. The default value is None (compare the elements directly).

reverse é um valor booleano. Se definido igual a True, então os elementos da lista são classificados como se cada comparação fosse reversa.

In general, the key and reverse conversion processes are much faster than specifying an equivalent cmp function. This is because cmp is called multiple times for each list element while key and reverse touch each element only once. Use functools.cmp_to_key() to convert an old-style cmp function to a key function.

A função embutida sorted() é garantida como estável. Uma ordem é estável se garantir não alterar a ordem relativa dos elementos que se comparam da mesma forma — isso é útil para ordenar em várias passagens (por exemplo, ordenar por departamento e depois por nível de salário).

Para selecionar exemplos e um breve tutorial de classificação, veja: ref: sortinghowto.

Novo na versão 2.4.

staticmethod(function)¶

Return a static method for function.

Um método estático não recebe um primeiro argumento implícito. Para declarar um método estático, use este idioma:

class C(object):
    @staticmethod
    def f(arg1, arg2, ...):
        ...

A forma @staticmethod é uma função de decorator – veja Function definitions para detalhes.

Um método estático pode ser chamado na classe (tal como C.f()) ou em uma instância (tal como C().f()).

Métodos estáticos em Python são similares àqueles encontrados em Java ou C++. Veja também classmethod() para uma variante útil na criação de construtores de classe alternativos.

Para mais informações sobre métodos estáticos, consulte A hierarquia de tipos padrão.

Novo na versão 2.2.

Alterado na versão 2.4: Function decorator syntax added.

class str(object='')¶

Return a string containing a nicely printable representation of an object. For strings, this returns the string itself. The difference with repr(object) is that str(object) does not always attempt to return a string that is acceptable to eval(); its goal is to return a printable string. If no argument is given, returns the empty string, ''.

For more information on strings see Sequence Types — str, unicode, list, tuple, bytearray, buffer, xrange which describes sequence functionality (strings are sequences), and also the string-specific methods described in the Métodos de String section. To output formatted strings use template strings or the % operator described in the String Formatting Operations section. In addition see the String Services section. See also unicode().

sum(iterable[, start])¶

Sums start and the items of an iterable from left to right and returns the total. start defaults to 0. The iterable’s items are normally numbers, and the start value is not allowed to be a string.

Para alguns casos de uso, existem boas alternativas para sum(). A maneira rápida e preferida de concatenar uma sequência de strings é chamando ''.join(sequence). Para adicionar valores de ponto flutuante com precisão estendida, consulte math.fsum(). Para concatenar uma série de iteráveis, considere usar itertools.chain().

Novo na versão 2.3.

super(type[, object-or-type])¶

Return a proxy object that delegates method calls to a parent or sibling class of type. This is useful for accessing inherited methods that have been overridden in a class. The search order is same as that used by getattr() except that the type itself is skipped.

The __mro__ attribute of the type lists the method resolution search order used by both getattr() and super(). The attribute is dynamic and can change whenever the inheritance hierarchy is updated.

Se o segundo argumento for omitido, o objeto super retornado é desacoplado. Se o segundo argumento é um objeto, isinstance(obj, type) deve ser verdadeiro. Se o segundo argumento é um tipo, issubclass(type2, type) deve ser verdadeiro (isto é útil para classmethods).

Nota

super() only works for new-style classes.

Existem dois casos de uso típicos para super. Em uma hierarquia de classes com herança única, super pode ser usado para se referir a classes-pai sem nomeá-las explicitamente, tornando o código mais sustentável. Esse uso é paralelo ao uso de super em outras linguagens de programação.

O segundo caso de uso é oferecer suporte à herança múltipla cooperativa em um ambiente de execução dinâmica. Esse caso de uso é exclusivo do Python e não é encontrado em idiomas ou linguagens compiladas estaticamente que suportam apenas herança única. Isso torna possível implementar “diagramas em losango”, onde várias classes base implementam o mesmo método. Um bom design determina que esse método tenha a mesma assinatura de chamada em todos os casos (porque a ordem das chamadas é determinada em tempo de execução, porque essa ordem se adapta às alterações na hierarquia de classes e porque essa ordem pode incluir classes de irmãos desconhecidas antes do tempo de execução).

Nos dois casos de uso, uma chamada típica de superclasse se parece com isso:

class C(B):
    def method(self, arg):
        super(C, self).method(arg)

Observe que super() é implementada como parte do processo de vinculação para procura explícita de atributos com ponto, tal como super().__getitem__(nome). Ela faz isso implementando seu próprio método __getattribute__() para pesquisar classes em uma ordem predizível que possui suporte a herança múltipla cooperativa. Logo, super() não é definida para procuras implícitas usando instruções ou operadores como super()[name].

Also note that super() is not limited to use inside methods. The two argument form specifies the arguments exactly and makes the appropriate references.

Para sugestões práticas sobre como projetar classes cooperativas usando super(), consulte o guia para uso de super().

Novo na versão 2.2.

tuple([iterable])¶

Return a tuple whose items are the same and in the same order as iterable’s items. iterable may be a sequence, a container that supports iteration, or an iterator object. If iterable is already a tuple, it is returned unchanged. For instance, tuple('abc') returns ('a', 'b', 'c') and tuple([1, 2, 3]) returns (1, 2, 3). If no argument is given, returns a new empty tuple, ().

tuple is an immutable sequence type, as documented in Sequence Types — str, unicode, list, tuple, bytearray, buffer, xrange. For other containers see the built in dict, list, and set classes, and the collections module.

class type(object)¶

class type(name, bases, dict)

With one argument, return the type of an object. The return value is a type object. The isinstance() built-in function is recommended for testing the type of an object.

With three arguments, return a new type object. This is essentially a dynamic form of the class statement. The name string is the class name and becomes the __name__ attribute; the bases tuple itemizes the base classes and becomes the __bases__ attribute; and the dict dictionary is the namespace containing definitions for class body and becomes the __dict__ attribute. For example, the following two statements create identical type objects:

>>> class X(object):
...     a = 1
...
>>> X = type('X', (object,), dict(a=1))

Novo na versão 2.2.

unichr(i)¶: Return the Unicode string of one character whose Unicode code is the integer i. For example, unichr(97) returns the string u'a'. This is the inverse of ord() for Unicode strings. The valid range for the argument depends how Python was configured – it may be either UCS2 [0..0xFFFF] or UCS4 [0..0x10FFFF]. ValueError is raised otherwise. For ASCII and 8-bit strings see chr().

Novo na versão 2.0.

unicode(object='')¶

unicode(object[, encoding[, errors]])

Return the Unicode string version of object using one of the following modes:

If encoding and/or errors are given, unicode() will decode the object which can either be an 8-bit string or a character buffer using the codec for encoding. The encoding parameter is a string giving the name of an encoding; if the encoding is not known, LookupError is raised. Error handling is done according to errors; this specifies the treatment of characters which are invalid in the input encoding. If errors is 'strict' (the default), a ValueError is raised on errors, while a value of 'ignore' causes errors to be silently ignored, and a value of 'replace' causes the official Unicode replacement character, U+FFFD, to be used to replace input characters which cannot be decoded. See also the codecs module.

If no optional parameters are given, unicode() will mimic the behaviour of str() except that it returns Unicode strings instead of 8-bit strings. More precisely, if object is a Unicode string or subclass it will return that Unicode string without any additional decoding applied.

For objects which provide a __unicode__() method, it will call this method without arguments to create a Unicode string. For all other objects, the 8-bit string version or representation is requested and then converted to a Unicode string using the codec for the default encoding in 'strict' mode.

For more information on Unicode strings see Sequence Types — str, unicode, list, tuple, bytearray, buffer, xrange which describes sequence functionality (Unicode strings are sequences), and also the string-specific methods described in the Métodos de String section. To output formatted strings use template strings or the % operator described in the String Formatting Operations section. In addition see the String Services section. See also str().

Novo na versão 2.0.

Alterado na versão 2.2: Support for __unicode__() added.

vars([object])¶

Retorna o atributo __dict__ para um módulo, classe, instância, or qualquer outro objeto com um atributo __dict__.

Objects such as modules and instances have an updateable __dict__ attribute; however, other objects may have write restrictions on their __dict__ attributes (for example, new-style classes use a dictproxy to prevent direct dictionary updates).

Sem um argumento, vars() funciona como locals(). Perceba que, o dicionário locals é apenas útil para leitura, pelo fato de alterações no dicionário locals serem ignoradas.

xrange(stop)¶
xrange(start, stop[, step]): This function is very similar to range(), but returns an xrange object instead of a list. This is an opaque sequence type which yields the same values as the corresponding list, without actually storing them all simultaneously. The advantage of xrange() over range() is minimal (since xrange() still has to create the values when asked for them) except when a very large range is used on a memory-starved machine or when all of the range’s elements are never used (such as when the loop is usually terminated with break). For more information on xrange objects, see XRange Type and Sequence Types — str, unicode, list, tuple, bytearray, buffer, xrange.

CPython implementation detail: xrange() is intended to be simple and fast. Implementations may impose restrictions to achieve this. The C implementation of Python restricts all arguments to native C longs (“short” Python integers), and also requires that the number of elements fit in a native C long. If a larger range is needed, an alternate version can be crafted using the itertools module: islice(count(start, step), (stop-start+step-1+2*(step<0))//step).

zip([iterable, ...])¶

This function returns a list of tuples, where the i-th tuple contains the i-th element from each of the argument sequences or iterables. The returned list is truncated in length to the length of the shortest argument sequence. When there are multiple arguments which are all of the same length, zip() is similar to map() with an initial argument of None. With a single sequence argument, it returns a list of 1-tuples. With no arguments, it returns an empty list.

The left-to-right evaluation order of the iterables is guaranteed. This makes possible an idiom for clustering a data series into n-length groups using zip(*[iter(s)]*n).

zip() em conjunto com o operador * pode ser usado para descompactar uma lista:

>>> x = [1, 2, 3]
>>> y = [4, 5, 6]
>>> zipped = zip(x, y)
>>> zipped
[(1, 4), (2, 5), (3, 6)]
>>> x2, y2 = zip(*zipped)
>>> x == list(x2) and y == list(y2)
True

Novo na versão 2.0.

Alterado na versão 2.4: Formerly, zip() required at least one argument and zip() raised a TypeError instead of returning an empty list.

__import__(name[, globals[, locals[, fromlist[, level]]]])¶

Nota

Esta é uma função avançada que não é necessária na programação diária do Python, ao contrário de importlib.import_module().

This function is invoked by the import statement. It can be replaced (by importing the __builtin__ module and assigning to __builtin__.__import__) in order to change semantics of the import statement, but nowadays it is usually simpler to use import hooks (see PEP 302). Direct use of __import__() is rare, except in cases where you want to import a module whose name is only known at runtime.

A função importa o módulo name, potencialmente usando os dados globals e locals para determinar como interpretar o nome em um contexto de pacote. O fromlist fornece os nomes de objetos ou submódulos que devem ser importados do módulo, fornecidos por name. A implementação padrão não usa seu argumento locals e usa seus globals apenas para determinar o contexto do pacote da instrução import.

level specifies whether to use absolute or relative imports. The default is -1 which indicates both absolute and relative imports will be attempted. 0 means only perform absolute imports. Positive values for level indicate the number of parent directories to search relative to the directory of the module calling __import__().

Quando a variável name está no formato package.module, normalmente, o pacote de nível superior (o nome até o primeiro ponto) é retornado, não o módulo nomeado por name. No entanto, quando um argumento fromlist não vazio é fornecido, o módulo nomeado por name é retornado.

Por exemplo, a instrução importar spam resulta em bytecode semelhante ao seguinte código:

spam = __import__('spam', globals(), locals(), [], -1)

A instrução import spam.ham resulta nesta chamada:

spam = __import__('spam.ham', globals(), locals(), [], -1)

Observe como __import__() retorna o módulo de nível superior aqui, porque este é o objeto vinculado a um nome pela instrução import.

Por outro lado, a instrução ``from spam.ham import eggs, sausage as saus’’ resulta em

_temp = __import__('spam.ham', globals(), locals(), ['eggs', 'sausage'], -1)
eggs = _temp.eggs
saus = _temp.sausage

Aqui, o módulo spam.ham é retornado de __import__(). A partir desse objeto, os nomes a serem importados são recuperados e atribuídos aos seus respectivos nomes.

Se você simplesmente deseja importar um módulo (potencialmente dentro de um pacote) pelo nome, use importlib.import_module().

Alterado na versão 2.5: The level parameter was added.

Alterado na versão 2.5: Keyword support for parameters was added.

3. Non-essential Built-in Functions¶

There are several built-in functions that are no longer essential to learn, know or use in modern Python programming. They have been kept here to maintain backwards compatibility with programs written for older versions of Python.

Python programmers, trainers, students and book writers should feel free to bypass these functions without concerns about missing something important.

apply(function, args[, keywords])¶: The function argument must be a callable object (a user-defined or built-in function or method, or a class object) and the args argument must be a sequence. The function is called with args as the argument list; the number of arguments is the length of the tuple. If the optional keywords argument is present, it must be a dictionary whose keys are strings. It specifies keyword arguments to be added to the end of the argument list. Calling apply() is different from just calling function(args), since in that case there is always exactly one argument. The use of apply() is equivalent to function(*args, **keywords).

Obsoleto desde a versão 2.3: Use function(*args, **keywords) instead of apply(function, args, keywords) (see Desempacotando listas de argumentos).

buffer(object[, offset[, size]])¶: The object argument must be an object that supports the buffer call interface (such as strings, arrays, and buffers). A new buffer object will be created which references the object argument. The buffer object will be a slice from the beginning of object (or from the specified offset). The slice will extend to the end of object (or will have a length given by the size argument).

coerce(x, y)¶: Return a tuple consisting of the two numeric arguments converted to a common type, using the same rules as used by arithmetic operations. If coercion is not possible, raise TypeError.

intern(string)¶: Enter string in the table of “interned” strings and return the interned string – which is string itself or a copy. Interning strings is useful to gain a little performance on dictionary lookup – if the keys in a dictionary are interned, and the lookup key is interned, the key comparisons (after hashing) can be done by a pointer compare instead of a string compare. Normally, the names used in Python programs are automatically interned, and the dictionaries used to hold module, class or instance attributes have interned keys.

Alterado na versão 2.3: Interned strings are not immortal (like they used to be in Python 2.2 and before); you must keep a reference to the return value of intern() around to benefit from it.

Notas de Rodapé

1: It is used relatively rarely so does not warrant being made into a statement.
2: Specifying a buffer size currently has no effect on systems that don’t have setvbuf(). The interface to specify the buffer size is not done using a method that calls setvbuf(), because that may dump core when called after any I/O has been performed, and there’s no reliable way to determine whether this is the case.
3: In the current implementation, local variable bindings cannot normally be affected this way, but variables retrieved from other scopes (such as modules) can be. This may change.

2. Funções Built-in¶

3. Non-essential Built-in Functions¶

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