numpy 2d数组操作，保持某些位置

Qfwfq 发表于 Dev

Qfwfq

我有两个2d numpy数组：

X2d = np.array([[0,4,5,0],
                [7,8,4,3],
                [0,0,9,8]])

Y2d = np.array([[1,0,4,8],
                [0,3,8,5],
                [0,6,0,8]])

#and I would like to get these two:

X2dresult = np.array([[0,0,5,0],
                      [0,8,4,3],
                      [0,0,0,8]])

Y2dresult = np.array([[0,0,4,0],
                      [0,3,8,5],
                      [0,0,0,8]])

因此，基本上我需要保持两个矩阵都大于0的那些位置。我可以使用numpy.where函数或类似的东西来获得这些结果吗？谢谢

阿什维尼乔杜里（Ashwini Chaudhary）

您可以使用按位与或或，numpy.where为此：

>>> X2d = np.array([[0,4,5,0],
...                 [7,8,4,3],
...                 [0,0,9,8]])
>>> 
>>> Y2d = np.array([[1,0,4,8],
...                 [0,3,8,5],
...                 [0,6,0,8]])
>>> indices = np.where(~((X2d > 0) & (Y2d > 0)))
>>> X2d[indices] = 0
>>> Y2d[indices] = 0
>>> X2d
array([[0, 0, 5, 0],
       [0, 8, 4, 3],
       [0, 0, 0, 8]])
>>> Y2d
array([[0, 0, 4, 0],
       [0, 3, 8, 5],
       [0, 0, 0, 8]])

我认为按位OR阅读更好，更清晰：

>>> X2d = np.array([[0,4,5,0],
...                 [7,8,4,3],
...                 [0,0,9,8]])
>>> 
>>> Y2d = np.array([[1,0,4,8],
...                 [0,3,8,5],
...                 [0,6,0,8]])
>>> indices = np.where((X2d == 0) | (Y2d == 0))
>>> X2d[indices] = 0
>>> Y2d[indices] = 0
>>> X2d
array([[0, 0, 5, 0],
       [0, 8, 4, 3],
       [0, 0, 0, 8]])
>>> Y2d
array([[0, 0, 4, 0],
       [0, 3, 8, 5],
       [0, 0, 0, 8]])