Zero out the column mean of a matrix:
>>> A = np.array([[1,2,3], [4,5,6], [7,8,9], [10, 11, 12]])
>>> mean = A.mean(axis=0)
>>> mean
array([ 5.5, 6.5, 7.5])
>>> A - mean
array([[-4.5, -4.5, -4.5],
[-1.5, -1.5, -1.5],
[ 1.5, 1.5, 1.5],
[ 4.5, 4.5, 4.5]])
10
11
12
7
8
9
4
5
6
1
2
3
-
=
5.5
6.5
7.5
5.5
6.5
7.5
5.5
6.5
7.5
5.5
6.5
7.5
4.5
1.5.
-1.5
-4.5
4.5
1.5
-1.5
-4.5
4.5
1.5
-1.5
-4.5