python取数组前几列_提取一个numpy矩阵的前n列

I have an array like this:

array([[-0.57098887, -0.4274751 , -0.38459931, -0.58593526],

[-0.22279713, -0.51723555, 0.82462029, 0.05319973],

[ 0.67492385, -0.69294472, -0.2531966 , 0.01403201],

[ 0.41086611, 0.26374238, 0.32859738, -0.80848795]])

Now I want to extract the following:

[-0.57098887, -0.4274751]

[-0.22279713, -0.51723555]

[ 0.67492385, -0.69294472]

[ 0.41086611, 0.26374238]

So basically just first 2 columns..

解决方案

If a is your array:

In [11]: a[:,:2]

Out[11]:

array([[-0.57098887, -0.4274751 ],

[-0.22279713, -0.51723555],

[ 0.67492385, -0.69294472],

[ 0.41086611, 0.26374238]])