所有代码先加这行解决中文乱码问题

# -*- coding: utf-8 -*-

版本区别注意：

py2.7： xrange();

py3.x: range();

1. 通用做法

data = [1,2,3,4,5,6,7,8]res = []for x in data:    if x >= 2:        res.append(x)print res

2. 高级:(函数式编程/列表解析/字典解析/集合解析)

#函数式编程res = filter(lambda x:x>=2,data)print res#列表解析res = [x for x in data if x>=2]print res#字典解析dic = {'a':23,'b':98,'c':0}res = {k:v for k,v in dic.iteritems() if v>90}print res#集合解析s = (1,2,3,4,5,6,7,8)res = {x for x in data if x>=2}print res

3. 三个实例

3.1 example1 列表解析

from random import randint#使用列表生成式生成10个元素data = [randint(-10,10) for _ in xrange(10)]print data#filter(func,sequence)res = filter(lambda x:x>=0,data)print res# 列表解析res = [x for x in data if x>=0]print res#Time: filter&列表解析#>>>代表在ipython下#>>> timeit filter(lambda x:x>=0,data)#>>> timeit [x for x in data if x>=0]# 结果：列表解析：432ns(纳秒)#       filter  ：1.4us(微秒)=1400ns#       1微秒等于1000纳秒res = [x for x in data if x>=0]print res

列表解析更快。大约快两三倍。

3.2 example2 字典解析

from random import randint# 某班有20个人，分数分布在60~100d = {x: randint(60,100) for x in xrange(1,21) }print dprint { k for k in d if k>10}print {v for v in d.values() if v>90}print {k for k in d.keys() if k>10}res = {k:v for k,v in d.iteritems() if v>90}print res

3.3 example3集合解析

from random import randintdata = [randint(-10,10) for _ in xrange(10)]s = set(data) print ssres = {x for x in s if x % 3 == 0}print sres