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python - scipy convolve2d 输出错误的值

转载 作者:太空宇宙 更新时间:2023-11-03 13:35:38 27 4
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这是我用来检查 convolve2d 正确性的代码

import numpy as np
from scipy.signal import convolve2d

X = np.random.randint(5, size=(10,10))
K = np.random.randint(5, size=(3,3))
print "Input's top-left corner:"
print X[:3,:3]
print 'Kernel:'
print K

print 'Hardcording the calculation of a valid convolution (top-left)'
print (X[:3,:3]*K)
print 'Sums to'
print (X[:3,:3]*K).sum()
print 'However the top-left value of the convolve2d result'
Y = convolve2d(X, K, 'valid')
print Y[0,0]

在我的电脑上,结果如下:

Input's top-left (3x3) corner:
[[0 0 0]
[1 1 2]
[1 3 0]]
Kernel:
[[4 1 1]
[0 3 3]
[2 1 2]]
Hardcording the calculation of a valid convolution (top-left)
[[0 0 0]
[0 3 6]
[2 3 0]]
Sums to
14
However the top-left value of the convolve2d result
10

背景故事:我一直在调试一个 convnet 库,不知何故梯度总是错误的。几周后,我得出结论认为一切正常,所以我徒手检查了 convolve2d 函数。

最佳答案

我认为问题在于您没有执行 SciPy 实现的内容。我不会详述细节或基础,只会为您提供解决方案:

反转内核。

>>> import numpy as np

>>> arr = np.array([[0, 0, 0],
[1, 1, 2],
[1, 3, 0]])

>>> kernel = np.array([[4, 1, 1],
[0, 3, 3],
[2, 1, 2]])

>>> from scipy.signal import convolve2d

>>> convolve2d(arr, kernel[::-1, ::-1])
array([[ 0, 0, 0, 0, 0],
[ 2, 3, 7, 4, 4],
[ 5, 13, 14, 12, 0],
[ 4, 14, 16, 6, 8],
[ 1, 4, 7, 12, 0]])

>>> convolve2d(arr, kernel[::-1, ::-1], 'valid')
array([[14]])

关于python - scipy convolve2d 输出错误的值,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/40247760/

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