Python之filter函数使用示例

#!/usr/bin/env python
# -*- coding:utf8 -*-

###########
#找出开头（或结尾）不含有ab的字符串并将其提取出来
##########

s = ['ab_iua','sh_ab','a_bak']
print()
def filter_start(array):
    ret = []
    for i in array:
        if not i.startswith('ab'):
            ret.append(i)
    return ret

print(s)
tmp = filter_start(s)
print(tmp)

###########
print()
def filter_test(f,array):
    tmp = []
    for i in array:
        if not f(i):  ###*******###
            tmp.append(i)
    return tmp

def sb_show(n):
    return n.endswith('ab')

print(s)

res = filter_test(sb_show,s)
print(res)

tmp = filter_test(lambda n:n.endswith("ab"),s)
print(tmp)

##############
print()
###filter函数
s = ['ab_iua','sh_ab','a_bak']
print(s)
print(filter_test(lambda n:n.endswith("ab"),s))
print(list(filter_test(lambda n:n.endswith("ab"),s)))

 filter遍历序列中的每一个元素，判断每个元素得到的布尔值，如果是true则留下来

student = [
    {'name':'abc','num':1},
    {'name':'def','num':2},
    {'name':'ljk','num':3},
]

print(list(filter(lambda s:s['num']<=2,student)))

==> [{'name': 'abc', 'num': 1}, {'name': 'def', 'num': 2}]