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}