remove zero lines 2-D numpy array

Question

I run a qr factorization in numpy which returns a list of ndarrays, namely Qand R:

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Answer 1

Because the data are not equal zero exactly, we need set a threshold value for zero such as 1e-6, use numpy.all with axis=1 to check the rows are zeros or not. Use numpy.where and numpy.diff to get the split positions, and call numpy.split to split the array into a list of arrays.

import numpy as np
[q,r] = np.linalg.qr(np.array([1,0,0,0,1,1,1,1,1]).reshape(3,3))
mask = np.all(np.abs(r) < 1e-6, axis=1)
pos = np.where(np.diff(mask))[0] + 1
result = np.split(r, pos)