numpy: split 1D array of chunks separated by nans into a list of the chunks

Question

I have a numpy array with only some values being valid and the rest being nan. example:

[nan,nan, 1 , 2 , 3 , nan, nan, 10, 11 , nan, nan, nan, 23, 1, nan,          


        

Answer 1

I'd use itertools.groupby -- It might be slightly faster:

from numpy import NaN as nan
import numpy as np
a = np.array([nan,nan, 1 , 2 , 3 , nan, nan, 10, 11 , nan, nan, nan, 23, 1, nan, 7, 8])
from itertools import groupby
result = [list(v) for k,v in groupby(a,np.isfinite) if k]
print result #[[1.0, 2.0, 3.0], [10.0, 11.0], [23.0, 1.0], [7.0, 8.0]]