Python函数化编程整理

1.映射函数

items=[1,2,3,4,5]
def inc(x):
return x+1
list(map(inc,items))

[2, 3, 4, 5, 6]

>>> a = [i+1 for i in range(3)]
>>> list(map((lambda x:x+5),a))

[5, 6, 7]

 

2.过滤函数

>>> list(filter((lambda x:x>1),a))

[2]

3.规约函数:将列表所有元素依次计算后返回唯一结果

累加：

>>> from functools import reduce

>>> reduce((lambda x,y:x+y),a)

45

累乘

>>> arr = [i+1 for i in range(4)]
>>> reduce((lambda x,y:x*y),arr)

24

4.lamdba函数：匿名函数，其他列子里有不列举

5.列表生成式

>>> a = [i+1 for i in range(3)]
>>> a

[1, 2, 3]

练习：列表[1,2,3,4,5]中过滤奇数。

>>> arr = list(filter((lambda x:x%2==0),[i+1 for i in range(5)]))
>>> arr

[2, 4]

练习：通过两个列表构建字典。

>>> a = [i+1 for i in range(3)]

>>> b = ['a','b','c']

>>> c = {i:j for i in a for j in b}

>>> c

{0: 'c', 1: 'c', 2: 'c'}