1表达方式

[表达式, for 变量 in 列表]

[表达式, for 变量 in 列表 if 条件]

2举例

ll = [1,2,3,4,5,6,7,8,9]
print [v*10, for v in ll if v>4]

输出：[50,60,70,80,90]

ll = [1,2,3,4,5,6,7,8,9]
timeslen = dict([(v,v*10), for v in ll])

建立字典{1:10,2:20,3:30,4:40,5:50,6:60,7:70,8:80,9:90}

列表推导式