Python之内置函数

内置函数

注：查看详细https://docs.python.org/3/library/functions.html#next

匿名函数

1 def calc(x):
2     return x+1
3 
4 
5 print(calc(10))
6 # print(lambda x:x+1)  # 匿名函数内存地址
7 
8 func = lambda x: x + 1
9 print(func(10))

高阶函数

　　满足任意一个条件：

　　1、函数的传入参数是一个函数名

　　2、函数的返回值是一个函数名

1.map内置函数   map(func, *iterables) --> map object

 1 num_l = [1, 2, 3, 4, 5, 6]
 2 # lambda x: x+1
 3 
 4 
 5 def add_one(x):
 6     return x+1
 7 
 8 
 9 def map_test(func, array):
10     """
11     模拟map内置函数
12     :param func: 传入的参数进行处理方法
13     :param array: 传入可迭代的对象
14     :return:
15     """
16     ret = []
17     for i in array:
18         res = func(i)
19         ret.append(res)
20     return ret
21 
22 
23 print(map_test(add_one, num_l))
24 print(map_test(lambda x: x+1, num_l))
25 res = map(lambda x: x+1, num_l)
26 print(list(res))
27 
28 
29 name = 'eric'
30 v = map(lambda x: x.upper(), name).__iter__()   # 把对象转成可迭代对象 遵行迭代协议
31 r = v.__next__()  # next直到StopIteration
32 print(r)
33 
34 # print(list(map(lambda x: x.upper(), name)))

map

2.filter函数

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 
 4 
 5 movie_person = ['eric_sb', 'alex_sb', 'lhf']
 6 
 7 
 8 def sb_show(x):
 9     return x.endswith('_sb')
10 
11 
12 def filter_test(func, array):
13     ret = []
14     for p in array:
15         if not func(p):
16             ret.append(p)
17     return ret
18 
19 
20 print(filter_test(sb_show, movie_person))
21 
22 print(list(filter(lambda x: not x.endswith('_sb'), movie_person)))

filter

3.reduce函数

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 
 4 
 5 from functools import reduce
 6 
 7 num_l = [1, 2, 3, 100]
 8 
 9 
10 def reduce_test(func, array, init=None):
11     if init is None:
12         res = array.pop(0)
13     else:
14         res = init
15     for num in num_l:
16         res = func(res, num)
17     return res
18 
19 
20 # print(reduce_test(lambda x, y: x * y, num_l))
21 # reduce：处理一个序列，然后把序列合并操作
22 print(reduce(lambda x, y: x * y, num_l, 2))
23 
24 
25 def reduce(function, sequence, initial=None):  # real signature unknown; restored from __doc__
26     """
27     reduce(function, sequence[, initial]) -> value
28 
29     Apply a function of two arguments cumulatively to the items of a sequence,
30     from left to right, so as to reduce the sequence to a single value.
31     For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) calculates
32     ((((1+2)+3)+4)+5).  If initial is present, it is placed before the items
33     of the sequence in the calculation, and serves as a default when the
34     sequence is empty.
35     """
36     pass

reduce

4.其它内置

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 
 4 
 5 # import re
 6 # some_text = 'a,b,,,,c d'
 7 # reObj = re.compile('[, ]+')  创建re对象
 8 # print(reObj.split(some_text))
 9 
10 
11 import re
12 
13 some_text = 'a,b,,,,c d'
14 print(re.split('[, ]+', some_text))  # 会导致重复re模块，降低匹配速度
15 print(complex('1+2j'))
16 
17 # print(complex('1 + 2j')) ValueError官方文档上
18 exec("print("hello, world")")
19 print(eval("1+2*2"))
20 a = '{"name":"alex"}'
21 print(eval(a))
22 print(float(2))
23 print(help(compile))
24 print(repr(1))  # 终端打开
25 # slice() 切片
26 # vars() 有点像locals()