Zero out the row mean of a matrix:
>>> import numpy as np
>>> A = np.array([[1,2,3], [4,5,6], [7,8,9], [10, 11, 12]])
>>> mean = A.mean(axis=1)
>>> mean
array([ 2., 5., 8., 11.])
>>> A - mean[:, np.newaxis]
array([[-1., 0., 1.],
[-1., 0., 1.],
[-1., 0., 1.],
[-1., 0., 1.]])
10
11
12
7
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9
4
5
6
1
2
3
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2.
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11.
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-
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=