Fast way to create numpy 1d bool array with known nonzero entry indexes

Question

Given a 1d np.ndarray containing a list of indexes that is True: [1, 2, 4], and length of the target np.ndarray: 6

How can we quickly construct the actual np.ndarray which should be [False, True, True, False, True, False]

Ehsan · Accepted Answer · 2020-07-12 20:26:11Z

2

idx = [1,2,3]
s = 6
a = np.zeros(s,dtype=bool)
a[idx] = True

output:

[False  True  True  True False False]

answered Jul 12, 2020 at 20:26

Ehsan

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5 Comments

Dude you are incredible! And so is numpy!

Yes! I will accept your answer as soon as Stackoverflow allows me, you answered too quick!

Oh, did not know there is a time limit. Thank you.

stackoverflow.com/questions/62866197/… Do you think you can answer this one as well?

@HuadongFeng Please check my answer on that and see if it is what you are looking for. Thank you.