內置函數

Built-in Functions

abs()

dict()

help()

min()

setattr()

all()

dir()

hex()

next()

slice()

any()

divmod()

id()

object()

sorted()

ascii()

enumerate()

input()

oct()

staticmethod()

bin()

eval()

int()

open()

str()

bool()

exec()

isinstance()

pow()

super()

bytes()

float()

iter()

print()

tuple()

callable()

format()

len()

property()

type()

chr()

frozenset()

list()

range()

vars()

classmethod()

getattr()

locals()

repr()

zip()

compile()

globals()

map()

reversed()

__import__()

complex()

hasattr()

max()

round()

bytearray()

filter()

issubclass()

pow()

super()

delattr()

hash()

memoryview()

set

截止到python版本3.6.2，現在python一共為我們提供了68個內置函數。它們就是python提供給你直接可以拿來使用的所有函數。

內置函數分類

作用域相關

基于字典的形式獲取局部變量和全局變量

globals()——獲取全局變量的字典

locals()——獲取執行本方法所在命名空間內的局部變量的字典

其他

輸入輸出相關

input()輸入

s = input("請輸入內容 ： ") #輸入的內容賦值給s變量

print(s) #輸入什么打印什么。數據類型是str

print輸出

def print(self, *args, sep=' ', end='\n', file=None): # known special case of print

"""

print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False)

file: 默認是輸出到屏幕，如果設置為文件句柄，輸出到文件

sep: 打印多個值之間的分隔符，默認為空格

end: 每一次打印的結尾，默認為換行符

flush: 立即把內容輸出到流文件，不作緩存

"""

f = open('tmp_file','w')

print(123,456,sep=',',file = f,flush=True)

from time import sleep

for i in range(0,101,2):

sleep(0.1)

str="*"*(i//2)

print('\r%s%%:%s'%(i,str),end="",flush=True)

數據類型相關

type(s)返回s的數據類型

s="abc"

print(type(s))#

內存相關

id(s) s是參數，返回一個變量的內存地址

hash(s) s是參數，返回一個可hash變量的哈希值，不可hash的變量被hash之后會報錯。

l1=[1,2,3]

l2=(1,2,3)

print(hash(l2))#2528502973977326415

print(hash(l1))#TypeError: unhashable type: 'list'

hash函數會根據一個內部的算法對當前可hash變量進行處理，返回一個int數字。

*每一次執行程序，內容相同的變量hash值在這一次執行過程中不會發生改變。

hash函數會根據一個內部的算法對當前可hash變量進行處理，返回一個int數字。

*每一次執行程序，內容相同的變量hash值在這一次執行過程中不會發生改變。

文件操作相關

open() 打開一個文件，返回一個文件操作符(文件句柄)

操作文件的模式有r,w,a,r+,w+,a+ 共6種，每一種方式都可以用二進制的形式操作(rb,wb,ab,rb+,wb+,ab+)

可以用encoding指定編碼.

模塊操作相關

__import__導入一個模塊

os = __import__('os')

print(os.path.abspath('.'))

幫助方法

help(s) s為函數名

help(str)

#輸出

class str(object)

| str(object='') -> str

| str(bytes_or_buffer[, encoding[, errors]]) -> str

|

| Create a new string object from the given object. If encoding or

| errors is specified, then the object must expose a data buffer

| that will be decoded using the given encoding and error handler.

| Otherwise, returns the result of object.__str__() (if defined)

| or repr(object).

| encoding defaults to sys.getdefaultencoding().

| errors defaults to 'strict'.

|

| Methods defined here:

|

| __add__(self, value, /)

| Return self+value.

|

| __contains__(self, key, /)

| Return key in self.

|

| __eq__(self, value, /)

| Return self==value.

|

| __format__(...)

| S.__format__(format_spec) -> str

|

| Return a formatted version of S as described by format_spec.

|

| __ge__(self, value, /)

| Return self>=value.

|

| __getattribute__(self, name, /)

| Return getattr(self, name).

|

| __getitem__(self, key, /)

| Return self[key].

|

| __getnewargs__(...)

|

| __gt__(self, value, /)

| Return self>value.

|

| __hash__(self, /)

| Return hash(self).

|

| __iter__(self, /)

| Implement iter(self).

|

| __le__(self, value, /)

| Return self<=value.

|

| __len__(self, /)

| Return len(self).

|

| __lt__(self, value, /)

| Return self

|

| __mod__(self, value, /)

| Return self%value.

|

| __mul__(self, value, /)

| Return self*value.n

|

| __ne__(self, value, /)

| Return self!=value.

|

| __new__(*args, **kwargs) from builtins.type

| Create and return a new object. See help(type) for accurate signature.

|

| __repr__(self, /)

| Return repr(self).

|

| __rmod__(self, value, /)

| Return value%self.

|

| __rmul__(self, value, /)

| Return self*value.

|

| __sizeof__(...)

| S.__sizeof__() -> size of S in memory, in bytes

|

| __str__(self, /)

| Return str(self).

|

| capitalize(...)

| S.capitalize() -> str

|

| Return a capitalized version of S, i.e. make the first character

| have upper case and the rest lower case.

|

| casefold(...)

| S.casefold() -> str

|

| Return a version of S suitable for caseless comparisons.

|

| center(...)

| S.center(width[, fillchar]) -> str

|

| Return S centered in a string of length width. Padding is

| done using the specified fill character (default is a space)

|

| count(...)

| S.count(sub[, start[, end]]) -> int

|

| Return the number of non-overlapping occurrences of substring sub in

| string S[start:end]. Optional arguments start and end are

| interpreted as in slice notation.

|

| encode(...)

| S.encode(encoding='utf-8', errors='strict') -> bytes

|

| Encode S using the codec registered for encoding. Default encoding

| is 'utf-8'. errors may be given to set a different error

| handling scheme. Default is 'strict' meaning that encoding errors raise

| a UnicodeEncodeError. Other possible values are 'ignore', 'replace' and

| 'xmlcharrefreplace' as well as any other name registered with

| codecs.register_error that can handle UnicodeEncodeErrors.

|

| endswith(...)

| S.endswith(suffix[, start[, end]]) -> bool

|

| Return True if S ends with the specified suffix, False otherwise.

| With optional start, test S beginning at that position.

| With optional end, stop comparing S at that position.

| suffix can also be a tuple of strings to try.

|

| expandtabs(...)

| S.expandtabs(tabsize=8) -> str

|

| Return a copy of S where all tab characters are expanded using spaces.

| If tabsize is not given, a tab size of 8 characters is assumed.

|

| find(...)

| S.find(sub[, start[, end]]) -> int

|

| Return the lowest index in S where substring sub is found,

| such that sub is contained within S[start:end]. Optional

| arguments start and end are interpreted as in slice notation.

|

| Return -1 on failure.

|

| format(...)

| S.format(*args, **kwargs) -> str

|

| Return a formatted version of S, using substitutions from args and kwargs.

| The substitutions are identified by braces ('{' and '}').

|

| format_map(...)

| S.format_map(mapping) -> str

|

| Return a formatted version of S, using substitutions from mapping.

| The substitutions are identified by braces ('{' and '}').

|

| index(...)

| S.index(sub[, start[, end]]) -> int

|

| Return the lowest index in S where substring sub is found,

| such that sub is contained within S[start:end]. Optional

| arguments start and end are interpreted as in slice notation.

|

| Raises ValueError when the substring is not found.

|

| isalnum(...)

| S.isalnum() -> bool

|

| Return True if all characters in S are alphanumeric

| and there is at least one character in S, False otherwise.

|

| isalpha(...)

| S.isalpha() -> bool

|

| Return True if all characters in S are alphabetic

| and there is at least one character in S, False otherwise.

|

| isdecimal(...)

| S.isdecimal() -> bool

|

| Return True if there are only decimal characters in S,

| False otherwise.

|

| isdigit(...)

| S.isdigit() -> bool

|

| Return True if all characters in S are digits

| and there is at least one character in S, False otherwise.

|

| isidentifier(...)

| S.isidentifier() -> bool

|

| Return True if S is a valid identifier according

| to the language definition.

|

| Use keyword.iskeyword() to test for reserved identifiers

| such as "def" and "class".

|

| islower(...)

| S.islower() -> bool

|

| Return True if all cased characters in S are lowercase and there is

| at least one cased character in S, False otherwise.

|

| isnumeric(...)

| S.isnumeric() -> bool

|

| Return True if there are only numeric characters in S,

| False otherwise.

|

| isprintable(...)

| S.isprintable() -> bool

|

| Return True if all characters in S are considered

| printable in repr() or S is empty, False otherwise.

|

| isspace(...)

| S.isspace() -> bool

|

| Return True if all characters in S are whitespace

| and there is at least one character in S, False otherwise.

|

| istitle(...)

| S.istitle() -> bool

|

| Return True if S is a titlecased string and there is at least one

| character in S, i.e. upper- and titlecase characters may only

| follow uncased characters and lowercase characters only cased ones.

| Return False otherwise.

|

| isupper(...)

| S.isupper() -> bool

|

| Return True if all cased characters in S are uppercase and there is

| at least one cased character in S, False otherwise.

|

| join(...)

| S.join(iterable) -> str

|

| Return a string which is the concatenation of the strings in the

| iterable. The separator between elements is S.

|

| ljust(...)

| S.ljust(width[, fillchar]) -> str

|

| Return S left-justified in a Unicode string of length width. Padding is

| done using the specified fill character (default is a space).

|

| lower(...)

| S.lower() -> str

|

| Return a copy of the string S converted to lowercase.

|

| lstrip(...)

| S.lstrip([chars]) -> str

|

| Return a copy of the string S with leading whitespace removed.

| If chars is given and not None, remove characters in chars instead.

|

| partition(...)

| S.partition(sep) -> (head, sep, tail)

|

| Search for the separator sep in S, and return the part before it,

| the separator itself, and the part after it. If the separator is not

| found, return S and two empty strings.

|

| replace(...)

| S.replace(old, new[, count]) -> str

|

| Return a copy of S with all occurrences of substring

| old replaced by new. If the optional argument count is

| given, only the first count occurrences are replaced.

|

| rfind(...)

| S.rfind(sub[, start[, end]]) -> int

|

| Return the highest index in S where substring sub is found,

| such that sub is contained within S[start:end]. Optional

| arguments start and end are interpreted as in slice notation.

|

| Return -1 on failure.

|

| rindex(...)

| S.rindex(sub[, start[, end]]) -> int

|

| Return the highest index in S where substring sub is found,

| such that sub is contained within S[start:end]. Optional

| arguments start and end are interpreted as in slice notation.

|

| Raises ValueError when the substring is not found.

|

| rjust(...)

| S.rjust(width[, fillchar]) -> str

|

| Return S right-justified in a string of length width. Padding is

| done using the specified fill character (default is a space).

|

| rpartition(...)

| S.rpartition(sep) -> (head, sep, tail)

|

| Search for the separator sep in S, starting at the end of S, and return

| the part before it, the separator itself, and the part after it. If the

| separator is not found, return two empty strings and S.

|

| rsplit(...)

| S.rsplit(sep=None, maxsplit=-1) -> list of strings

|

| Return a list of the words in S, using sep as the

| delimiter string, starting at the end of the string and

| working to the front. If maxsplit is given, at most maxsplit

| splits are done. If sep is not specified, any whitespace string

| is a separator.

|

| rstrip(...)

| S.rstrip([chars]) -> str

|

| Return a copy of the string S with trailing whitespace removed.

| If chars is given and not None, remove characters in chars instead.

|

| split(...)

| S.split(sep=None, maxsplit=-1) -> list of strings

|

| Return a list of the words in S, using sep as the

| delimiter string. If maxsplit is given, at most maxsplit

| splits are done. If sep is not specified or is None, any

| whitespace string is a separator and empty strings are

| removed from the result.

|

| splitlines(...)

| S.splitlines([keepends]) -> list of strings

|

| Return a list of the lines in S, breaking at line boundaries.

| Line breaks are not included in the resulting list unless keepends

| is given and true.

|

| startswith(...)

| S.startswith(prefix[, start[, end]]) -> bool

|

| Return True if S starts with the specified prefix, False otherwise.

| With optional start, test S beginning at that position.

| With optional end, stop comparing S at that position.

| prefix can also be a tuple of strings to try.

|

| strip(...)

| S.strip([chars]) -> str

|

| Return a copy of the string S with leading and trailing

| whitespace removed.

| If chars is given and not None, remove characters in chars instead.

|

| swapcase(...)

| S.swapcase() -> str

|

| Return a copy of S with uppercase characters converted to lowercase

| and vice versa.

|

| title(...)

| S.title() -> str

|

| Return a titlecased version of S, i.e. words start with title case

| characters, all remaining cased characters have lower case.

|

| translate(...)

| S.translate(table) -> str

|

| Return a copy of the string S in which each character has been mapped

| through the given translation table. The table must implement

| lookup/indexing via __getitem__, for instance a dictionary or list,

| mapping Unicode ordinals to Unicode ordinals, strings, or None. If

| this operation raises LookupError, the character is left untouched.

| Characters mapped to None are deleted.

|

| upper(...)

| S.upper() -> str

|

| Return a copy of S converted to uppercase.

|

| zfill(...)

| S.zfill(width) -> str

|

| Pad a numeric string S with zeros on the left, to fill a field

| of the specified width. The string S is never truncated.

|

| ----------------------------------------------------------------------

| Static methods defined here:

|

| maketrans(x, y=None, z=None, /)

| Return a translation table usable for str.translate().

|

| If there is only one argument, it must be a dictionary mapping Unicode

| ordinals (integers) or characters to Unicode ordinals, strings or None.

| Character keys will be then converted to ordinals.

| If there are two arguments, they must be strings of equal length, and

| in the resulting dictionary, each character in x will be mapped to the

| character at the same position in y. If there is a third argument, it

| must be a string, whose characters will be mapped to None in the result.

在控制臺執行help()進入幫助模式。可以隨意輸入變量或者變量的類型。輸入q退出

或者直接執行help(o)，o是參數，查看和變量o有關的操作。。。

和調用相關

callable(s)，s是參數，看這個變量是不是可調用。

如果s是一個函數名，就會返回True

def func():pass

print(callable(func))#True

print(callable(123))#Flase

查看參數所屬類型的所有內置方法

dir() 默認查看全局空間內的屬性，也接受一個參數，查看這個參數內的方法或變量

dir(list)

['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']

和數字相關

數字——數據類型相關：bool，int，float，complex

數字——進制轉換相關：bin，oct，hex

數字——數學運算：abs，divmod，min，max，sum，round，pow

和數據結構相關

序列——列表和元組相關的：list和tuple

序列——字符串相關的：str，format，bytes，bytearry，memoryview，ord，chr，ascii，repr

ret=bytearray('xiaozhangmen',encoding='utf-8')

print(ret)#bytearray(b'xiaozhangmen')

ret = memoryview(bytes('你好',encoding='utf-8'))

print(len(ret))

print(bytes(ret[:3]).decode('utf-8'))

print(bytes(ret[3:]).decode('utf-8'))

序列：reversed，slice

l=[1,2,3,4,5,6]

l.reverse()

print(l)#[6, 5, 4, 3, 2, 1]

l=[1,2,3,4,5,6]

sli=slice(1,4,2)#slice看起來返回的是一個規則，拿到這個規則后再對列表進行操作

print(l[sli])#[2, 4]

數據集合——字典和集合：dict，set,frozenset

數據集合：len，sorted，enumerate，all，any，zip，filter，map

filter：使用指定方法過濾可迭代對象的元素

def is_odd(x):

return x % 2 == 1

print(filter(is_odd,[1,2,3,4,5,6]))#

print(list(filter(is_odd,[1,2,3,4,5,6])))#[1, 3, 5]

map：python中的map函數應用于每一個可迭代的項，返回的是一個結果list。如果有其他的可迭代參數傳進來，map函數則會把每一個參數都以相應的處理函數進行迭代處理。map()函數接收兩個參數，一個是函數，一個是序列，map將傳入的函數依次作用到序列的每個元素，并把結果作為新的list返回。

def pow(x):

return x**2

print(map(pow,[0,1,2,3]))#

print(list(map(pow,[0,1,2,3])))#[0, 1, 4, 9]

匿名函數

匿名函數：為了解決那些功能很簡單的需求而設計的一句話函數

匿名函數格式：

函數名 = lambda 參數 ：返回值

#參數可以有多個，用逗號隔開

#匿名函數不管邏輯多復雜，只能寫一行，且邏輯執行結束后的內容就是返回值

#返回值和正常的函數一樣可以是任意數據類型

匿名函數實例

#如把下面函數改為匿名函數

def add(x,y):

return x+y

add1=lambda x,y:x+y

print(add(1,2))

print(add1(1,2))

面試題筆記：

現有兩個元組(('a'),('b')),(('c'),('d'))，請使用python中匿名函數生成列表[{'a':'c'},{'b':'d'}]

#答案一

test = lambda t1,t2 :[{i:j} for i,j in zip(t1,t2)]

print(test(t1,t2))

#答案二

print(list(map(lambda t:{t[0]:t[1]},zip(t1,t2))))

#還可以這樣寫

print([{i:j} for i,j in zip(t1,t2)])

1.下面程序的輸出結果是：

d = lambda p:p*2

t = lambda p:p*3

x = 2

x = d(x)

x = t(x)

x = d(x)

print x

2.現有兩元組(('a'),('b')),(('c'),('d')),請使用python中匿名函數生成列表[{'a':'c'},{'b':'d'}]

3.以下代碼的輸出是什么？請給出答案并解釋。

def multipliers():

return [lambda x:i*x for i in range(4)]

print([m(2) for m in multipliers()])

請修改multipliers的定義來產生期望的結果。

以上這篇基于python內置函數與匿名函數詳解就是小編分享給大家的全部內容了，希望能給大家一個參考，也希望大家多多支持腳本之家。

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