Matching arrays of different shape in python numpy

Question

I have a big 2d bitewise array (0s and 1s only) and a small one (3x3).

I want to see where the big array matches the small one, i.e. i, j for which

big_array[i-1:i+2, j-1:j+2] == small_array

There could be more than one (i,j) that satisfies the condition. How do I do this without writing a double nested i, j loop?

I adapted this answer to my case. stride_tricks is very fast. stackoverflow.com/questions/4936620/… — fmonegaglia
– fmonegaglia, Commented Nov 13, 2014 at 10:44

erthalion · Accepted Answer · 2014-10-19 09:58:00Z

2

I hope, this code is what you need:

import numpy as np

big_array = np.array(...)
small_array = np.array(...)

for (i, j), _ in np.ndenumerate(big_array[:-2, :-2]):
    if (big_array[i:i+3, j:j+3] == small_array).all():
        print (i, j)

answered Oct 19, 2014 at 9:58

erthalion

3,2923 gold badges25 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Matching arrays of different shape in python numpy

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related