无法从多个NumPy数组中检索所需的索引

Question

无法从多个NumPy数组中检索所需的索引

3

我有4个形状相同的numpy数组（即2d）。我需要知道最后一个数组(d)中小于20的元素的索引，但这些d的索引应位于数组(a)元素为1的区域内；同时数组(b)和(c)的元素不为1。

我的尝试如下：

mask = (a == 1)|(b != 1)|(c != 1)

answer = d[mask | d < 20]

现在，我需要将d的这些区域设置为1；并将d的所有其他区域设置为0。

d[answer] = 1
d[d!=1] = 0
print d

我无法解决这个问题。你怎么解决的？

import numpy as np

a = np.array([[0,0,0,1,1,1,1,1,0,0,0],
                 [0,0,0,1,1,1,1,1,0,0,0],
                 [0,0,0,1,1,1,1,1,0,0,0],
                 [0,0,0,1,1,1,1,1,0,0,0],
                 [0,0,0,1,1,1,1,1,0,0,0],
                 [0,0,0,1,1,1,1,1,0,0,0]])

b = np.array([[0,0,0,1,1,0,0,0,0,0,0],
                 [0,0,0,0,0,0,1,1,0,0,0],
                 [0,0,0,1,0,1,0,0,0,0,0],
                 [0,0,0,1,1,1,0,1,0,0,0],
                 [0,0,0,0,0,0,1,0,0,0,0],
                 [0,0,0,0,1,0,1,0,0,0,0]])

c = np.array([[0,0,0,0,0,0,1,0,0,0,0],
                 [0,0,0,0,0,0,0,0,0,0,0],
                 [0,0,0,0,0,0,1,1,0,0,0],
                 [0,0,0,0,0,0,1,0,0,0,0],
                 [0,0,0,0,1,0,0,0,0,0,0],
                 [0,0,0,0,0,1,0,0,0,0,0]])


d = np.array([[0,56,89,67,12,28,11,12,14,8,240],
                 [1,57,89,67,18,25,11,12,14,9,230],
                 [4,51,89,87,19,20,51,92,54,7,210],
                 [6,46,89,67,51,35,11,12,14,6,200],
                 [8,36,89,97,43,67,81,42,14,1,220],
                 [9,16,89,67,49,97,11,12,14,2,255]])

- Borys

1个回答

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- YS-L · Accepted Answer

应该将条件 AND 起来，而不是 OR。您可以先获取表示所需区域的布尔数组/掩码，然后基于它修改 d:

mask = (a == 1) & (b != 1) & (c != 1) & (d < 20)
d[mask] = 1
d[~mask] = 0
print d

输出：

[[0 0 0 0 0 0 0 1 0 0 0]
 [0 0 0 0 1 0 0 0 0 0 0]
 [0 0 0 0 1 0 0 0 0 0 0]
 [0 0 0 0 0 0 0 0 0 0 0]
 [0 0 0 0 0 0 0 0 0 0 0]
 [0 0 0 0 0 0 0 1 0 0 0]]