在python中只选取列表中某一纵列的方法

> a=random.randint(1,6,(5,3))
> a
array([[5, 3, 1],
    [5, 5, 1],
    [5, 1, 3],
    [1, 4, 3],
    [5, 1, 2]])
> b=a.tolist()
> b#选取b列表的前2列
[[5, 3, 1], [5, 5, 1], [5, 1, 3], [1, 4, 3], [5, 1, 2]]
> c=mat(b)
> c
matrix([[5, 3, 1],
    [5, 5, 1],
    [5, 1, 3],
    [1, 4, 3],
    [5, 1, 2]])
> d=c[:,0:2]
> d#将d转化回列表即可
matrix([[5, 3],
    [5, 5],
    [5, 1],
    [1, 4],
    [5, 1]])