Python列表推导式(List comprehension)

列表推导式(list comprehension)简介

简单示例1：

#按行遍历一个文件，大写后输出
print [line.rstrip() for line in open('test.txt')]
#using if
#在list comprehension中使用if判断
print [line.rstrip() for line in open('test.txt') if line[0]=='n']

简单示例2：

testList = [1,2,3,4]
def mul2(x):
print x*2
[mul2(i) for i in testList]
#add some if logic
#仍然是添加if判断
print '-----if logic:'
[mul2(i) for i in testList if i%2==0]

list comprehension替代嵌套循环

#nested loop
for x in [1,2,3]:
for y in [1,2,3]:
z = x*y
print str(x)+'*'+str(y)+' is: '+str(z)

print [x*y for x in [1,2,3] for y in  [1,2,3]]