python 选取一列数据库 python选取某些列

>>> 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]])