1578 lines
34 KiB
Markdown
1578 lines
34 KiB
Markdown
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# Python 内置函数:简要概述
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> 原文：<https://www.askpython.com/python/built-in-methods/python-built-in-functions-brief-overview>
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内置函数是编程语言中已经存在的函数。在本文中，让我们通过例子来理解这些函数。
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* * *
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## [abs()](https://www.askpython.com/python/built-in-methods/python-abs-function)
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```py
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abs(number)
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```
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该函数返回一个*数*的绝对值。该参数可以是整数、浮点数或复数，如果是复数，则返回数字的大小。
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```py
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print(abs(10))
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print(abs(-210))
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print(abs(2 + 3j)) #complex number
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```
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**输出:**
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10
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210
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3 . 56386 . 38638686667
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## alter_)
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```py
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aiter(async iterable)
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```
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这个函数为[异步迭代](https://docs.python.org/3/glossary.html#term-asynchronous-iterable)返回一个[异步迭代器](https://docs.python.org/3/glossary.html#term-asynchronous-iterator)。这是 python 3.10 中的一个新函数。
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此函数的示例实现。(更多示例请访问[此处](https://python.hotexamples.com/examples/coroutils.generator/-/aiter/python-aiter-function-examples.html))
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```py
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async def aitersync(iterable):
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results = []
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async for x in aiter(iterable):
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results.append(x)
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return iter(results)
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```
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## [all()](https://www.askpython.com/python/built-in-methods/all-method-in-python)
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```py
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all(iterable)
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```
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该函数采用 iterable(iterable 是可以迭代方式使用的对象，或者在*中用于*循环。例如:列表、字符串、字典、集合、元组等)作为参数，并在两种情况下返回真值。
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1. 当 iterable 的所有元素都为真时
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2. 当 iterable 为空时
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```py
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#Below list wil return false as all the elements are not true.
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list1 = [10, 20, 30, 40, 50, false]
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print(all(list1)
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#Below set will return true as the set is empty
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set1 = {}
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print(all(set1))
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#Below dictionary wil return true as all elements of the dictonary are true.
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dict1 = {1: "Ask", 2: "Python"}
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print(all(dict1))
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```
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## [any()](https://www.askpython.com/python/built-in-methods/any-method-in-python)
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```py
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any(iterable)
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```
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该函数也将 iterable 作为参数，如果 iterable 的任何元素为 true，则返回 true。如果 iterable 为空，则返回 false。
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```py
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#Below list wil return True even when some the elements are not true.
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list1 = [10, 20, 30, 40, 50, false]
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print(all(list1)
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#Below set will return False as the set is empty
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set1 = {}
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print(all(set1))
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```
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## [ascii()](https://www.askpython.com/python/built-in-methods/python-ascii-function)
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```py
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ascii(object)
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```
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该函数返回对象的可打印版本。在非 ascii 字符的情况下，它用转义字符替换它们。
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```py
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x = ascii("åsk python")
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print(x)
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```
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**输出:** '\xe5sk python '
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字符被替换为转义字符。
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## [bin()](https://www.askpython.com/python/built-in-methods/python-bin-function)
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```py
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bin(int)
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```
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该函数返回指定整数的二进制版本。返回字符串总是以前缀`0b`开头。
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```py
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num = bin(7)
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print(num)
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```
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输出:0b111
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## [bool()](https://www.askpython.com/python/built-in-methods/python-bool-method)
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```py
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bool(object)
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```
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该函数返回指定对象的布尔值(真或假)。如果对象为真，函数将返回真；如果对象为假，或无，或零(0)，或空，函数将返回假。
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```py
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#below object will return False, as it is empty
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list1 = bool()
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print(list1)
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#below object will return False, as it is 0
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list2 = bool(0)
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print(list2)
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#below object will return True, as it is non-empty
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nums = bool({1,2,3,4,5})
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orint(nums)
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```
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## [bytearray()](https://www.askpython.com/python/built-in-methods/python-bytearray-function)
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```py
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bytearray(x, encoding, error)
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```
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这个函数返回一个新的字节数组。它将对象转换为 bytearray 对象，或者创建特定所需大小的空 bytearray 对象。它有 3 个参数
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1. x:源参数
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* 如果它是一个*整数*，数组将具有该大小，并用空字节初始化。
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* 如果是一个*字符串*，还必须给出*编码*(以及可选的*错误*)参数
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2. 编码:如果源是字符串，则为字符串的编码。
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3. 错误:如果源是字符串，编码转换失败时要采取的操作。
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```py
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arr = bytearray(5)
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print(arr)
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str = "Ask Python"
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arr1 = bytearray(str, 'utf-8')
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print(arr1)
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```
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**输出:**
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bytearray(b ' \ x00 \ x00 \ x00 \ x00 \ x00 ')
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字节数组(b'Ask Python ')
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## [字节()](https://www.askpython.com/python/built-in-methods/python-bytes)
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```py
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byte(x, encoding, error)
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```
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这个函数返回一个新的“字节”对象。它是 bytearray()的不可变版本，这意味着 bytes()返回一个不可修改的对象。参数也与 bytearray()的相同
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1. x:源参数
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* 如果它是一个*整数*，数组将具有该大小，并用空字节初始化。
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* 如果是一个*字符串*，还必须给出*编码*(以及可选的*错误*)参数
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2. 编码:如果源是字符串，则为字符串的编码。
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3. 错误:如果源是字符串，编码转换失败时要采取的操作。
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```py
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arr = bytes([1,2,3,4,5])
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print(arr)
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```
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**输出:** b'\x01\x02\x03\x04\x05 '
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## [callable()](https://www.askpython.com/python/built-in-methods/python-callable-method)
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```py
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callable(object)
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```
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如果对象参数是可调用的，该函数返回 true，否则返回 False。如果返回 True，调用仍然有可能失败，但是如果返回 False，调用对象将永远不会成功。
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```py
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def x():
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a = 100
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print(callable(x))
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```
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**输出:**真
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## [chr()](https://www.askpython.com/python/built-in-methods/python-chr-and-ord-methods)
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```py
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chr(int)
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```
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这个函数返回一个字符，这个字符的 Unicode 等于 integer int 的 Unicode。整数的范围是 0 到 1，114，111。如果整数超出定义的范围，该函数将返回 *ValueError* ，如果参数为非整数，则返回 *TypeError* 。
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```py
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num = chr(99)
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print(num)
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```
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输出:c
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## [classmethod()](https://www.askpython.com/python/oops/python-classmethod)
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```py
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#considered un-Pythonic
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classmethod(function)
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#new version
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@classmethod
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def func(cls, args...)
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```
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这个函数将一个函数作为参数，并将其转换为一个类方法。(类方法绑定到类，而不是对象，所以它不需要类实例)@classsmethod 是 class method 的装饰形式。
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创建 classmethod 示例:
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```py
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#defining class
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class Employee:
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salary = 10000
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dept: 'HR'
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def printSalary(cls):
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print('The employee earns', cls.salary, 'per month.')
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#creating classmethod
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Employee.printSalary = classmethod(Employee.printSalary)
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Employee.printSalary()
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```
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产出:员工月薪 10000
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## [编译()](https://www.askpython.com/python/built-in-methods/what-is-python-compile-function)
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```py
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compile(source, filename, mode, flag, dont_inherit, optimize)
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```
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这个函数将源代码转换成代码或 AST 对象。如果编译的源代码无效，函数返回`*SyntaxError*`,如果源代码包含空字节，函数返回`*ValueError*`。传递参数有:
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1. source:(强制)要编译的源代码可以是任何东西，如 AST 对象、字符串等
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2. filename:(强制)读取源文件的文件名，如果不存在这样的文件，自己命名。
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3. mode:(强制)指定必须编译哪种代码
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* eval–如果源包含单个表达式
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* exec–如果源包含语句块
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* single–如果源包含单个交互式语句
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4. flag 和 dont_inherit:(可选)控制应该激活哪些编译器选项，以及应该允许哪些未来功能。默认值分别为 0 和 false。
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5. optimize:(可选)指定编译器的优化级别；`-1`的默认值
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## [复杂()](https://www.askpython.com/python/built-in-methods/python-complex-method)
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```py
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complex(real, imaginary)
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```
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该函数返回给定的实数值和虚数值。它将字符串或数字转换成复数。如果第一个参数是一个字符串，它将被解释为一个复数，并且必须在没有第二个参数的情况下调用函数。第二个参数不能是字符串。如果省略了任何一个参数——实数或虚数，那么缺省值仍然是 0，并且构造函数充当类似 int 和 float 的数字转换。如果两个参数都省略，则返回 0j。
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```py
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z0 = complex(9,-8)
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print(z0)
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z1 = complex()
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print(z1)
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z2 = complex(10)
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print(z2)
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z3 = complex('10-4j')
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print(z3)
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z4 = complex('5-7j','7')
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print(z4)
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```
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**输出:**
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(9-8j)
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0j
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(10+0j)
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(10-4j)
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类型错误:如果第一个参数是字符串，则 complex()不能接受第二个参数
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## [delattr()](https://www.askpython.com/python/built-in-methods/python-delattr-function)
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```py
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delattr(object, attribute)
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```
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如果对象允许，这个函数会删除指定的属性。第一个参数指定从哪个对象中删除属性，第二个属性指定必须删除什么
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```py
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class Employee:
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Name= "Alex"
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|
|
Dept = "HR"
|
|||
|
|
Salary = 15000
|
|||
|
|
City = "Mumbai"
|
|||
|
|
|
|||
|
|
delattr(Employee, 'Salary')
|
|||
|
|
#Salary attribute gets deleted from the Employee
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
## 字典()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
dict(keyword arguments)
|
|||
|
|
class dict(**kwarg)
|
|||
|
|
class dict(mapping, **kwarg)
|
|||
|
|
class dict(iterable, **kwarg)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该功能
|
|||
|
|
|
|||
|
|
该功能
|
|||
|
|
|
|||
|
|
这个函数创建一个新的字典。dict 对象是 dictionary 类。class dict()返回一个新字典，它由一个可选的位置参数和一组可能为空的关键字参数初始化。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
d1 = dict(Name ="Alex", Salary =15000, City ="Mumbai")
|
|||
|
|
|
|||
|
|
print(d1)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
{ '姓名':'亚历克斯'，'薪金':15000，'城市':'孟买' }
|
|||
|
|
|
|||
|
|
## [dir() ](https://www.askpython.com/python/built-in-methods/python-dir-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
dir(object)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
当没有提供参数时，该函数返回当前局部范围内的名称列表。当参数存在时，它返回该对象的有效属性列表。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
s1 = {10, 20, 30, 40,}
|
|||
|
|
|
|||
|
|
print(dir(s1))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
['__and__ '，' __class__ '，' __contains__ '，' __delattr__ '，' __dir__ '，' __doc__ '，' __format__ '，' __ge__ '，' __getattribute__ '，' __gt__ '，' __hash__ '，' __iand__ '，' __init__ '，' __init_subclass__ '，'，' __ior__ '，'，' __isub
|
|||
|
|
|
|||
|
|
## [时尚()](https://www.askpython.com/python/built-in-methods/python-divmod-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
divmod(dividend, divisor)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
此函数返回由作为参数传递的数字的商和余数组成的数字对。它将为非数字参数返回 TypeError。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
dividend = 110
|
|||
|
|
divisor = 4
|
|||
|
|
nums = divmod(dividend, divisor)
|
|||
|
|
|
|||
|
|
print(nums)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:** (27，2)
|
|||
|
|
|
|||
|
|
## [枚举()](https://www.askpython.com/python/built-in-methods/python-enumerate-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
enumerate(iterable, start)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
此函数返回 iterable 的枚举对象( *iterable* 必须是序列 eg- tuple)。它向 iterable 添加一个计数器(从*开始*，默认为 0)。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
a = ('Monday', 'Tuesday', 'Wednesday','Thursday')
|
|||
|
|
b = enumerate(a)
|
|||
|
|
|
|||
|
|
#notice the difference in output
|
|||
|
|
print(list(a))
|
|||
|
|
print(list(b))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
['星期一'，'星期二'，'星期三'，'星期四']
|
|||
|
|
|
|||
|
|
[(0，'星期一')，(1，'星期二')，(2，'星期三')，(3，'星期四')]
|
|||
|
|
|
|||
|
|
## eval()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
eval(expression, globals, locals)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
此函数计算作为参数传递的表达式，如果表达式是有效的 Python 语句，它将被执行。这些参数是:
|
|||
|
|
|
|||
|
|
1. 表达式:要计算的字符串/表达式
|
|||
|
|
2. globals(可选):必须是字典
|
|||
|
|
3. 局部变量(可选):可以是任何映射对象。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
a = 10
|
|||
|
|
b = 2
|
|||
|
|
c = 'print(a * a + b)'
|
|||
|
|
|
|||
|
|
eval(c)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:** 102
|
|||
|
|
|
|||
|
|
## [exec()](https://www.askpython.com/python/built-in-methods/python-exec-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
exec(object, globals, locals)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数不返回任何值，它不返回任何值。这是一个支持 Python 代码动态执行的函数。对象必须是字符串或代码对象。如果它是一个代码对象，那么它只是被执行，但是在字符串的情况下，它首先被解析为一组 Python 语句，然后被执行。参数与 eval()相同，只是 eval()中的表达式被 exec()中的对象所更改
|
|||
|
|
|
|||
|
|
## [过滤器()](https://www.askpython.com/python/built-in-methods/python-filter-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
filter(function, iterable)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
顾名思义，这个函数通过函数过滤 iterable，检查该项是否被接受。它返回经过筛选的 iterable。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
def Result(x):
|
|||
|
|
if x < 30:
|
|||
|
|
return False
|
|||
|
|
else:
|
|||
|
|
return True
|
|||
|
|
|
|||
|
|
marks = [60, 91, 12, 29, 30, 41]
|
|||
|
|
pass_or_not = filter(Result, marks)
|
|||
|
|
|
|||
|
|
for x in pass_or_not:
|
|||
|
|
print(x)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
输出: 60 91 30 41
|
|||
|
|
|
|||
|
|
## [float()](https://www.askpython.com/python/built-in-methods/python-float-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
float(value)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回由一个值构造的浮点数。值可以是数字或字符串。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
x_int = 25
|
|||
|
|
y_float = float(x_int)
|
|||
|
|
|
|||
|
|
print(x_int)
|
|||
|
|
print(y_float)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
Twenty-five
|
|||
|
|
|
|||
|
|
Twenty-five
|
|||
|
|
|
|||
|
|
## [格式()](https://www.askpython.com/python/string/python-format-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
format(value, format)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数根据作为参数传递的指定格式返回格式化值。默认的*格式*是一个空字符串，但是，有一个大多数内置类型都使用的标准格式语法:[格式规范迷你语言](https://docs.python.org/3/library/string.html#formatspec)。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
# binary format - b
|
|||
|
|
x = 7
|
|||
|
|
print(format(x, "b"))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:** 111
|
|||
|
|
|
|||
|
|
## [frozenset()](https://www.askpython.com/python/built-in-methods/python-frozenset)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
frozenset(iterable)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回一个新的 set 或 frozenset 对象，其元素取自 *iterable* 。一个集合的元素必须是可散列的(如果它有一个在其生命周期中从不改变的散列值)。要表示集合的集合，内部集合必须是 frozenset 对象。如果没有指定 *iterable* ，则返回一个新的空集。
|
|||
|
|
|
|||
|
|
## [getattr()](https://www.askpython.com/python/built-in-methods/python-getattr-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
getattr(object, attribute, default)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数返回指定的属性。第一个参数指定从哪个对象中找到属性，第二个属性指定必须找到什么(属性)。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
class Employee:
|
|||
|
|
name = 'Alex'
|
|||
|
|
city = 'Mumbai'
|
|||
|
|
|
|||
|
|
Engineer = Employee()
|
|||
|
|
name = getattr(Engineer, 'name')
|
|||
|
|
print(name)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**亚历克斯
|
|||
|
|
|
|||
|
|
## [globals()](https://www.askpython.com/python/built-in-methods/python-globals)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
globals()
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数返回实现当前模块名称空间的字典。global()的输出将显示当前程序的所有全局变量和其他符号。
|
|||
|
|
|
|||
|
|
## [hasattr()](https://www.askpython.com/python/built-in-methods/python-hasattr-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
hasattr(object, attribute)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
如果指定的对象中存在指定的属性，则该函数返回 true，如果该属性不存在，则返回 false。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
class Employee:
|
|||
|
|
name = 'Alex'
|
|||
|
|
city = 'Mumbai'
|
|||
|
|
|
|||
|
|
Engineer = Employee()
|
|||
|
|
x = hasattr(Engineer, 'name')
|
|||
|
|
print(x)
|
|||
|
|
|
|||
|
|
y = hasattr(Engineer,'salary')
|
|||
|
|
print(y)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
真实的
|
|||
|
|
|
|||
|
|
错误的
|
|||
|
|
|
|||
|
|
## [哈希()](https://www.askpython.com/python/built-in-methods/python-hash-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
hash(object)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数返回对象的哈希值(如果有的话)。哈希值是用于在字典查找过程中快速比较字典键的整数。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
x1 = 'Ask Python'
|
|||
|
|
print('Ask Python: ', hash(x1))
|
|||
|
|
|
|||
|
|
x2 = 3.147
|
|||
|
|
print('3.147: ',hash(x2))
|
|||
|
|
|
|||
|
|
x3 = 71
|
|||
|
|
print('71:', hash(x3))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
求 Python:-1041620088632976012
|
|||
|
|
3.147:338958922354412547
|
|||
|
|
71:71
|
|||
|
|
|
|||
|
|
## [帮助()](https://www.askpython.com/python/built-in-methods/python-help-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
help(object)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数调用内置的帮助系统。它旨在用于交互式使用。在 python shell 上尝试这个函数。
|
|||
|
|
|
|||
|
|
* 如果*没有给出参数*，交互式帮助系统在解释器控制台上启动。
|
|||
|
|
* 如果参数是一个*字符串*，那么该字符串将被作为模块、函数、类、方法、关键字或文档主题的名称进行查找，并在控制台上打印一个帮助页面。
|
|||
|
|
* 如果参数是*任何其他类型的对象*，则生成关于该对象的帮助页面。
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
help() with no arguments
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
Help() with arguments
|
|||
|
|
|
|||
|
|
## [十六进制()](https://www.askpython.com/python/built-in-methods/python-hex-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
hex(number)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数将指定的数字转换成十六进制值。返回字符串总是以`0x`开头。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
x1 = hex(-44)
|
|||
|
|
print(x1)
|
|||
|
|
|
|||
|
|
x2 = hex(321)
|
|||
|
|
print(x2)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
-0x2c
|
|||
|
|
|
|||
|
|
0x141
|
|||
|
|
|
|||
|
|
## [id()](https://www.askpython.com/python/id-function-in-python)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
id(object)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数返回“身份”(唯一 id——这是一个整数，保证在对象的生命周期中是唯一的和恒定的。)的对象。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
x0 = 10
|
|||
|
|
print(id(x0))
|
|||
|
|
|
|||
|
|
x1 = 11
|
|||
|
|
print(id(x1))
|
|||
|
|
|
|||
|
|
x2 = x1
|
|||
|
|
print(id(x2))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
Nine million seven hundred and fifty-six thousand five hundred and twelve
|
|||
|
|
|
|||
|
|
Nine million seven hundred and fifty-six thousand five hundred and forty-four
|
|||
|
|
|
|||
|
|
Nine million seven hundred and fifty-six thousand five hundred and forty-four
|
|||
|
|
|
|||
|
|
## [输入()](https://www.askpython.com/python/built-in-methods/python-input-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
input(prompt)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数用于接收用户的输入。该函数从 input 中读取一行，将其转换为一个字符串(去掉尾随换行符)，然后返回该字符串。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
String1 = input('Input from the user: ')
|
|||
|
|
print('The input:', String1)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
来自用户的输入:询问 Python
|
|||
|
|
|
|||
|
|
## int()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
int(value)
|
|||
|
|
int (value, base)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回一个整数对象，该对象由一个数字或字符串*值*构成。如果没有给定参数，那么函数将返回 0。*基*是可选的，表示*值*的数字系统。它可以是 0、2、8、10 或 16。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
#base 2 -> binary number
|
|||
|
|
print(int('0b11101',2))
|
|||
|
|
|
|||
|
|
#base 16 -> hexadecimal number
|
|||
|
|
x2 = 0xC1
|
|||
|
|
print(int('0xC1',16))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
Twenty-nine
|
|||
|
|
|
|||
|
|
One hundred and ninety-three
|
|||
|
|
|
|||
|
|
## [isinstance()](https://www.askpython.com/python/built-in-methods/python-isinstance)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
isinstance(object, classinfo)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回一个布尔值。如果*对象*参数是指定的 *classinfo* 参数或其子类的实例，则返回 true。否则返回 false。如果 *classinfo* 参数不是类型或类型元组，则该函数返回 TypeError。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
numset = {1, 2, 3}
|
|||
|
|
print('Checking for set: ', isinstance(numset, set))
|
|||
|
|
print('Checking for list: ', isinstance(numset, list))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
检查集合:真
|
|||
|
|
检查列表:假
|
|||
|
|
|
|||
|
|
## [issubclass()](https://www.askpython.com/python/built-in-methods/python-issubclass-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
issubclass(class, classinfo)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回一个布尔值，如果*类*参数是*类信息*参数的子类，则返回 true，否则返回 false
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
class company:
|
|||
|
|
Office= 'AskPython'
|
|||
|
|
|
|||
|
|
class employee(company):
|
|||
|
|
name = 'Alex'
|
|||
|
|
Office = company
|
|||
|
|
|
|||
|
|
print(issubclass(employee, company))
|
|||
|
|
print(issubclass(employee, employee)) #every class is its own subclass
|
|||
|
|
print(issubclass(company, employee))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
真实的
|
|||
|
|
|
|||
|
|
真实的
|
|||
|
|
|
|||
|
|
错误的
|
|||
|
|
|
|||
|
|
## [iter()](https://www.askpython.com/python/python-iter-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
iter(object, sentinel)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数迭代器为给定的对象参数返回一个对象，直到取出*标记*为止。Sentinel 是可选的，它是用于表示序列结束的值。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
list1 = iter(["North", "East", "South", "West"])
|
|||
|
|
|
|||
|
|
print(next(list1))
|
|||
|
|
print(next(list1))
|
|||
|
|
print(next(list1))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
北
|
|||
|
|
|
|||
|
|
东方
|
|||
|
|
|
|||
|
|
南方
|
|||
|
|
|
|||
|
|
## len()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
len(object)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回长度，即一个*对象*的项数。*对象*参数可以是字符串、字节、元组、列表或范围等序列，甚至可以是字典、集合等集合。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
l1 = len([10,20,30,40])
|
|||
|
|
print(l1)
|
|||
|
|
|
|||
|
|
set1 = len({1,2,3,4,5,6,7})
|
|||
|
|
print(set1)
|
|||
|
|
|
|||
|
|
sent = len("Ask Python")
|
|||
|
|
print(sent)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
four
|
|||
|
|
|
|||
|
|
seven
|
|||
|
|
|
|||
|
|
Ten
|
|||
|
|
|
|||
|
|
## 列表()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
list(iterable)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数创建一个作为参数传递的 iterable 列表。在没有参数的情况下，该函数将创建一个空列表。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
string1 = 'Ask Python'
|
|||
|
|
string2 = list(string1)
|
|||
|
|
|
|||
|
|
print(string1)
|
|||
|
|
print(string2)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
求 Python
|
|||
|
|
['A '，' s '，' k '，' '，' P '，' y '，' t '，' h '，' o '，' n']
|
|||
|
|
|
|||
|
|
## [本地人()](https://www.askpython.com/python/built-in-methods/python-locals-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
locals()
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数返回一个代表当前本地符号表的字典。它还在必要时更新局部符号表。这个函数没有任何参数。它在函数块中返回自由变量，但在类块中不返回。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
print(locals())
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
<samp>{'In': ["，' locals()']，' Out': {}，' _ '::，' __ ':，' __builtin__ ':，' _ _ builtin _ _ ':，' __name__': '__main__ '，' _dh': ['/home/repl']，' _i ':"，' _i1': 'locals()'，' _ih': ["，' locals()']，' _ii ':"，' _iii ':"，' _oh '::':':' '</samp>
|
|||
|
|
|
|||
|
|
## [地图()](https://www.askpython.com/python/built-in-methods/map-method-in-python)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
map(function, iterables)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数将指定为参数的函数应用于作为参数传递的 iterable 的每一项，并返回结果迭代器。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
def solve_nums(n,m,k):
|
|||
|
|
return n*m+k
|
|||
|
|
|
|||
|
|
numbers = (1, 2, 3, 4)
|
|||
|
|
result = map(solve_nums,(1,2,3),(10,10,10),(1,2,3))
|
|||
|
|
print(result)
|
|||
|
|
print(list(result))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
<map object="" at=""></map>
|
|||
|
|
|
|||
|
|
[11, 22, 33]
|
|||
|
|
|
|||
|
|
## [max()](https://www.askpython.com/python/built-in-methods/python-max-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
max(n1, n2, n3, ...)
|
|||
|
|
max(iterable)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回一个*可迭代*参数中最大的项，或传递的两个或多个参数中最大的项(n1，n2…)。对于字符串参数，最大的项是按字母顺序排序的 iterable 的最后一项。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
str1 = max("India","China", "Dubai")
|
|||
|
|
print(str1)
|
|||
|
|
|
|||
|
|
nums = max(-2, -9, -12)
|
|||
|
|
print(nums)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
印度
|
|||
|
|
|
|||
|
|
-2
|
|||
|
|
|
|||
|
|
## 内存视图()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
memoryview(object)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
顾名思义，该函数返回对象的“memory view”；memoryview 允许您通过创建内存视图对象来访问对象的内部缓冲区。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
str = memoryview(b"Ask Python")
|
|||
|
|
|
|||
|
|
print(str)
|
|||
|
|
|
|||
|
|
#Unicode of the first character
|
|||
|
|
print(str[0])
|
|||
|
|
|
|||
|
|
#Unicode of the second character
|
|||
|
|
print(str[4])
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
Sixty-five
|
|||
|
|
|
|||
|
|
Eighty
|
|||
|
|
|
|||
|
|
## [min()](https://www.askpython.com/python/built-in-methods/python-min-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
min(n1, n2, n3, ...)
|
|||
|
|
min(iterable)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回一个*可迭代*参数中的最小项，或者两个或多个传递参数中的最小项(n1，n2…)。对于字符串参数，最小的项是按字母顺序排序的 iterable 的第一项。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
str1 = min("India","China", "Dubai")
|
|||
|
|
print(str1)
|
|||
|
|
|
|||
|
|
nums = min(-2, -9, -12)
|
|||
|
|
print(nums)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
中国
|
|||
|
|
|
|||
|
|
-12
|
|||
|
|
|
|||
|
|
## 下一个()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
next(iterable, default)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数检索指定的 *iterable* 的下一项。默认值是可选的，并且返回默认的*值*，直到 iterable 到达它的最终项。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
nums = iter([10,20,30])
|
|||
|
|
|
|||
|
|
#the next element -> 1st
|
|||
|
|
nums_1 = next(nums)
|
|||
|
|
print(nums_1)
|
|||
|
|
|
|||
|
|
#the next element -> 2nd
|
|||
|
|
nums_2 = next(nums)
|
|||
|
|
print(nums_2)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
Ten
|
|||
|
|
|
|||
|
|
Twenty
|
|||
|
|
|
|||
|
|
## [object()](https://www.askpython.com/python/built-in-methods/python-object-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
x = object()
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数不接受任何参数。它返回一个新的无特征的对象。一个对象拥有所有 Python 类实例共有的方法。它是所有阶级的基础
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
abc = object()
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
当创建输出“abc”对象时
|
|||
|
|
|
|||
|
|
## [oct()](https://www.askpython.com/python/built-in-methods/python-oct-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
oct(x)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
此函数将指定的数字转换为十八进制值。返回字符串总是以`0` o 开始。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
x1 = oct(-44)
|
|||
|
|
print(x1)
|
|||
|
|
|
|||
|
|
x2 = oct(321)
|
|||
|
|
print(x2)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
-0o54
|
|||
|
|
0o501
|
|||
|
|
|
|||
|
|
## [打开()](https://www.askpython.com/python/built-in-methods/python-open-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
open(file, mode='r', buffering=- 1, encoding=None, errors=None, newline=None, closefd=True, opener=None)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数打开文件并返回一个相应的 file 对象。如果找不到指定的文件，该函数将返回 OSError。这些参数是
|
|||
|
|
|
|||
|
|
* 文件–提供路径名，它是一个类似路径的对象
|
|||
|
|
* mode-这是一个可选字符串，指定文件打开的模式。以下是一些常用的模式
|
|||
|
|
|
|||
|
|
| `'r'` | 打开以供阅读(默认) |
|
|||
|
|
| `'w'` | 打开进行写入，首先截断文件 |
|
|||
|
|
| `'x'` | 以独占方式打开，如果文件已经存在，则失败 |
|
|||
|
|
| `'a'` | 打开以供写入，追加到文件的末尾(如果存在) |
|
|||
|
|
| `'b'` | 二进制 |
|
|||
|
|
| `'t'` | 文本模式(默认) |
|
|||
|
|
| `'+'` | 打开以进行更新(读取和写入) |
|
|||
|
|
|
|||
|
|
Modes and their description
|
|||
|
|
|
|||
|
|
* 缓冲–这是一个可选字符串，用于设置缓冲策略
|
|||
|
|
* encoding–这是一个可选字符串，用于说明编码格式
|
|||
|
|
* errors–这是一个可选字符串，用于解决编码/解码错误
|
|||
|
|
* newline–这是一个可选字符串，用于说明换行模式如何工作
|
|||
|
|
* closefd–这是一个可选字符串，默认情况下必须为 true 如果给定或否则，将发生异常。
|
|||
|
|
* opener–它是一个可选字符串，返回一个打开的文件描述符
|
|||
|
|
|
|||
|
|
## [ord()](https://www.askpython.com/python/built-in-methods/python-chr-and-ord-methods)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
ord(ch)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数只是返回所传递参数的 Unicode 码位的整数表示。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
print(ord('T'))
|
|||
|
|
print(ord('1'))
|
|||
|
|
print(ord('@'))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
84
|
|||
|
|
49
|
|||
|
|
64
|
|||
|
|
|
|||
|
|
## [pow()](https://www.askpython.com/python/built-in-methods/python-pow)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
pow(number, exponential, modulus)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回一个值，该值等于*数*的*指数*次方。modulus 参数是可选的，如果存在，则返回 mod of number。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
print(pow(2,0))
|
|||
|
|
print(pow(0, 2))
|
|||
|
|
print(pow(2,3,3)) #(2*2*2)/3
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
1
|
|||
|
|
0
|
|||
|
|
2
|
|||
|
|
|
|||
|
|
## [print()](https://www.askpython.com/python/built-in-methods/python-print-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
print(object(s), sep=separator, end=end, file=file, flush=flush)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
顾名思义，这个函数将对象打印到文本流文件中，由 *sep* 分隔，后跟 *end* 。除了*对象*之外的所有其他参数都是可选的。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
nums = [1,2,3,4]
|
|||
|
|
|
|||
|
|
print("Numbers are: ", nums, sep='0', end='\n')
|
|||
|
|
print("Ask Python")
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
数字是:0[1，2，3，4]
|
|||
|
|
问 Python
|
|||
|
|
|
|||
|
|
## [属性()](https://www.askpython.com/python/built-in-methods/python-property-decorator)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
property(fget=None, fset=None, fdel=None, doc=None)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数采用四个可选参数，并返回 property 属性。
|
|||
|
|
|
|||
|
|
* *fget* 用于获取一个属性值。
|
|||
|
|
* *偏移*用于设置属性值。
|
|||
|
|
* *fdel* 用于删除属性值。
|
|||
|
|
* *doc* 为属性创建一个 docstring。
|
|||
|
|
|
|||
|
|
## [范围()](https://www.askpython.com/python/built-in-methods/python-range-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
range(start, stop, step)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数根据传递的参数返回一个不可变的数字序列。如果传递了一个参数，那么该函数会将其视为一个 *stop* 参数。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
nums = [1,2,3,4,5,6,7,8,9,10]
|
|||
|
|
|
|||
|
|
nums = range(5)
|
|||
|
|
print(list(nums))
|
|||
|
|
|
|||
|
|
#2, and 10 are considered start and stop respectively
|
|||
|
|
nums = range(2,10)
|
|||
|
|
print(list(nums))
|
|||
|
|
|
|||
|
|
#increament step 2
|
|||
|
|
nums = range(2,10,2)
|
|||
|
|
print(list(nums))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
[0，1，2，3，4]
|
|||
|
|
【2，3，4，5，6，7，8，9】
|
|||
|
|
【2，4，6，8】
|
|||
|
|
|
|||
|
|
## repr()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
repr(object)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回一个字符串，该字符串包含一个对象的可打印表示。在大多数情况下，它返回相同的对象。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
string1 = 'Ask Python'
|
|||
|
|
print(repr(string1))
|
|||
|
|
|
|||
|
|
nums1 = [1,2,3,4]
|
|||
|
|
print(repr(nums1))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
问 Python'
|
|||
|
|
[1，2，3，4]
|
|||
|
|
|
|||
|
|
## [反转()](https://www.askpython.com/python/built-in-methods/python-reversed-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
reversed(sequence)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回指定*序列*参数的逆序。这里，序列可以是任何可索引的可迭代的，例如列表、元组、集合等。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
list1 = [1, 2, 4, 3, 5]
|
|||
|
|
print(list(reversed(list1)))
|
|||
|
|
|
|||
|
|
tuple1 = ('A','S','K',' ','P','Y','T','H','O','N')
|
|||
|
|
print(list(reversed(tuple1)))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
[5，3，4，2，1]
|
|||
|
|
['N '，' O '，' H '，' T '，' Y '，' P '，' '，' K '，' S '，' A']
|
|||
|
|
|
|||
|
|
## [回合()](https://www.askpython.com/python/built-in-methods/python-round)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
round(number, ndigits)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回一个四舍五入到小数点后*位数*的数字。 *ndigits 参数是可选的，如果不提供，函数将返回最接近的整数*。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
print('1.8 -> ',round(1.8))
|
|||
|
|
print('1.2 -> ',round(1.2))
|
|||
|
|
print('1.5678 (2 decimal points)-> ',round(1.5678,2))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
1-> 1
|
|||
|
|
1.8->2
|
|||
|
|
1.2->1
|
|||
|
|
1.5678(小数点后两位)- > 1.57
|
|||
|
|
|
|||
|
|
## 集合()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
set(iterable)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数为指定的 iterable 参数构造一个集合。如果没有指定参数，那么函数将构造一个空集。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
print(set()) #empty set will be constructed
|
|||
|
|
print(set(('A','S','K',' ','P','Y','T','H','O','N')))
|
|||
|
|
print(set(('Ask Python')))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
set()
|
|||
|
|
{'S '，' O '，' K '，' A '，' H '，' N '，' P '，' Y '，' ' }
|
|||
|
|
{'t '，' S '，' A '，' N '，' P '，' Y '，' O '，' K '，' '，' h'}
|
|||
|
|
|
|||
|
|
## [setattr()](https://www.askpython.com/python/python-setattr-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
setattr(object, name, value)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数用于设置或修改指定的*对象*参数中的名称及其值。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
class Employee:
|
|||
|
|
name = 'Atlas'
|
|||
|
|
|
|||
|
|
emp = Employee()
|
|||
|
|
print('Before:', emp.name)
|
|||
|
|
|
|||
|
|
#modifying the name using setattr()
|
|||
|
|
setattr(emp, 'name', 'Ryle')
|
|||
|
|
print('After:', emp.name)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
之前:阿特拉斯
|
|||
|
|
之后:赖尔
|
|||
|
|
|
|||
|
|
## [切片()](https://www.askpython.com/python/built-in-methods/python-slice-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
slice(stop)
|
|||
|
|
slice(start, stop, step)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回对象的一个切片，该切片是在*开始*和*停止*参数之间的一个对象的项目。这里*步*和*开始*是可选参数。如果未提及*开始*，则功能*从第 1 项开始*。步长参数用于指示增量，默认值设置为无。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
string1 = 'Ask Python'
|
|||
|
|
slice_object1 = slice(6)
|
|||
|
|
print(string1[slice_object1])
|
|||
|
|
|
|||
|
|
nums1 = [1,2,3,4,5,6,7,8,9,10,11]
|
|||
|
|
slice_object2 = slice(1, 6, 2)
|
|||
|
|
print(nums1[slice_object2]) #increament by 2
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
询问 Py
|
|||
|
|
[2，4，6]
|
|||
|
|
|
|||
|
|
## [已排序()](https://www.askpython.com/python/built-in-methods/python-sorted-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
sorted(iterable, key=key, reverse=reverse)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数从 *iterable* 中的项目返回一个新的排序列表。*键是一个*可选参数，用于指定返回列表的顺序。*倒档也是一个*可选参数。它是一个布尔值，如果降序，则返回 true，如果升序，则返回 false。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
nums = [50,20,40,10,30]
|
|||
|
|
print(sorted(nums))
|
|||
|
|
print(sorted(nums,reverse = True))
|
|||
|
|
|
|||
|
|
string1 = 'AskPython'
|
|||
|
|
print(sorted(string1))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
[10，20，30，40，50]
|
|||
|
|
【50，40，30，20，10】
|
|||
|
|
[' A '，' P '，' h '，' k '，' n '，' o '，' s '，' t '，' y']
|
|||
|
|
|
|||
|
|
## str()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
str(object=b'', encoding='utf-8', errors='strict')
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数返回一个 [`str`](https://docs.python.org/3/library/stdtypes.html#str) 对象的一个版本。*编码*参数指定编码格式，默认值设置为 utf-8。*错误*参数指定解码失败时如何响应。它可以是严格的，忽略的或替换的。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
s1 = bytes('AskPython', encoding='utf-8',errors='strict')
|
|||
|
|
print(str(s1, encoding='ascii', errors='ignore'))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
AskPython
|
|||
|
|
|
|||
|
|
## [sum()](https://www.askpython.com/python/built-in-methods/python-sum-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
sum(iterable, start=0)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
该函数返回所有项目的总和加上*开始*参数。start 参数是可选的，默认情况下被认为是 0。iterable 的项目只能是数字。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
nums = [10,20,30,40,50]
|
|||
|
|
|
|||
|
|
print(sum(nums))
|
|||
|
|
print(sum(nums,3))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
150
|
|||
|
|
153
|
|||
|
|
|
|||
|
|
## [超级()](https://www.askpython.com/python/built-in-methods/super-method-in-python)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
super(object)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数返回对象的父类或兄弟类。这对于访问在类中被重写的继承方法很有用。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
class Employee(object):
|
|||
|
|
def __init__(self, emp):
|
|||
|
|
print(emp, 'works for AskPython')
|
|||
|
|
|
|||
|
|
class emp(Employee):
|
|||
|
|
def __init__(self):
|
|||
|
|
super().__init__('Alex')
|
|||
|
|
|
|||
|
|
emp1 = emp()
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
亚历克斯为 AskPython 工作
|
|||
|
|
|
|||
|
|
## 元组()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
tuple(iterable)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数为指定的 *iterable* 参数构造一个元组。如果没有指定参数，那么函数将构造一个空元组。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
print(tuple()) #empty tuple will be constructed
|
|||
|
|
print(tuple([10,20,30,40]))
|
|||
|
|
print(tuple(('Ask Python')))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出:**
|
|||
|
|
|
|||
|
|
()
|
|||
|
|
(10，20，30，40)
|
|||
|
|
('A '，' s '，' k '，' '，' P '，' y '，' t '，' h '，' o '，' n ')
|
|||
|
|
|
|||
|
|
## [type()](https://www.askpython.com/python/built-in-methods/python-type-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
type(object)
|
|||
|
|
type(name, bases, dict)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数以两种不同的方式工作。
|
|||
|
|
|
|||
|
|
* 如果参数对象被传递，那么它将返回对象的类型。
|
|||
|
|
* 如果传递了三个参数，那么它返回一个新类型的对象。*名称*字符串是类名。*基*元组包含基类。如果为空，则添加一个对象，即所有类的最终基。*字典*包含了类体的属性和方法定义。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
nums= {10,20,30,40}
|
|||
|
|
print(type(nums))
|
|||
|
|
|
|||
|
|
class Employee:
|
|||
|
|
name: 'Atlas'
|
|||
|
|
emp = Employee()
|
|||
|
|
print(type(emp))
|
|||
|
|
|
|||
|
|
sample1 = type('AskPython',(Employee,) ,dict(x1='a', x2='b'))
|
|||
|
|
print(type(sample1))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出**:
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
<class 'main.employee'>
|
|||
|
|
<class 'type'>
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
## [乌鸦()](https://www.askpython.com/python/built-in-methods/python-vars-method)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
vars(object)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
这个函数返回指定对象参数的字典映射属性(__dict__)。如果没有提到参数，那么函数返回局部范围内的方法。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
print (vars())
|
|||
|
|
print(vars(tuple))
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出**:
|
|||
|
|
|
|||
|
|
{'name': 'main '，' doc': None，' package': None，' loader ':' spec ':None，' annotations': {，' builtins': }
|
|||
|
|
{'repr ':，' hash ':，' getattribute ':，' lt ':，' le ':' eq ':，' ne ':，' gt ':，' ge ':' ITER ':，' len ':，' getitem ':，' add ':，' mul ':，' rmul ':' contains ':，' new ':，' getnewargs ':，' index ':，' count ':' doc ':"内置不可变\ n \ n 如果没有给定参数，构造函数将返回一个空元组。\ n 如果指定了 iterable，则从 iterable 的项初始化元组。\ n \ n 如果参数是元组，则返回值是同一个对象。}
|
|||
|
|
|
|||
|
|
## [zip()](https://www.askpython.com/python/built-in-methods/python-zip-function)
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
zip(*iterables)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
基于作为参数传递的 iterable 的元组的这个函数迭代器。
|
|||
|
|
|
|||
|
|
* 如果没有指定参数，函数将返回一个空迭代器。
|
|||
|
|
* 如果指定了单个 iterable 参数，该函数将返回一个元组迭代器，每个元组只有一个元素。
|
|||
|
|
* 如果指定了多个 iterables 参数，该函数将返回一个元组迭代器，每个元组包含所有 iterables 中的元素。
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
nums = [1, 2, 3, 4]
|
|||
|
|
string1 = ['North', 'East', 'West','South']
|
|||
|
|
|
|||
|
|
# Two iterables are passed
|
|||
|
|
x = zip(nums, string1)
|
|||
|
|
list1 = list(x)
|
|||
|
|
print(list1)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
**输出**:
|
|||
|
|
|
|||
|
|
[(1，'北')，(2，'东')，(3，'西')，(4，'南')]
|
|||
|
|
|
|||
|
|
## __ 导入 _ _()
|
|||
|
|
|
|||
|
|
```py
|
|||
|
|
__import__(name, globals=None, locals=None, fromlist=(), level=0)
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
当语句调用此函数时，此函数用于更改导入语句的语义。反而用进口挂钩更好。该功能很少使用，我们不鼓励使用该功能。
|
|||
|
|
|
|||
|
|
## 结论
|
|||
|
|
|
|||
|
|
Python 是最好解释的语言之一。内置函数使得更容易有效地使用它。在本文中，我们介绍了 python 中所有可用的内置函数，以及它们的用法和示例。
|
|||
|
|
|
|||
|
|
如需更多参考资料，请点击[此处。](https://docs.python.org/3/library/functions.html)
|