Numpy

非副本视图的子视图

import numpy as np

>> x = np.array([[12,5,2,4],
                  [7,6,8,8],
                  [1,6,7,7]])
array([[12,  5,  2,  4],
       [ 7,  6,  8,  8],
       [ 1,  6,  7,  7]])

1.取前2行，前2列
>> x_sub = x[:2,:2]
array([[12,  5],
       [ 7,  6]])

2.修改x_sub 
>> x_sub[0][0] = 99
>> print(x_sub)
[[99  5]
 [ 7  6]]

3.此时打印原来的x,发现x也被修改了
>> print(x)
[[99  5  2  4]
 [ 7  6  8  8]
 [ 1  6  7  7]]