Extract separate non-zero blocks from array

Question

having an array like this for example:

[1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1]

What\'s the fastest way in Pytho

Answer 1

Have a look at scipy.ndimage.measurements.label:

import numpy as np
from scipy.ndimage.measurements import label

x = np.asarray([1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1])
labelled, numfeats = label(x)
indices = [np.nonzero(labelled == k) for k in np.unique(labelled)[1:]]

indices contains exactly what you asked for. Note that, depending on your ultimate goal, labelled might also give you useful (extra) information.