Select based on neighbouring elements

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Chapters
00:00 Select Based On Neighbouring Elements
01:30 Accepted Answer Score 3
01:51 Thank you

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Full question
https://stackoverflow.com/questions/4805...

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https://meta.stackexchange.com/help/lice...

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Tags
#python #numpy

#avk47

ACCEPTED ANSWER

Score 3

Get mask of elements greater than the threshold and simply use binary_dilation with an appropriate kernel to select north+east+west+south ones, like so -

In [20]: from scipy.ndimage.morphology import binary_dilation

In [21]: mask = test >= 9

In [22]: kernel = np.array([[0,1,0],[1,0,1],[0,1,0]])

In [23]: binary_dilation(mask, kernel)
Out[23]: 
array([[False, False, False, False],
       [False,  True,  True,  True],
       [ True,  True,  True,  True],
       [ True,  True,  True,  True]], dtype=bool)