Question

How to apply NumPy where condition on a matrix in Python

Answer 1

import numpy as np

a = np.array([[0, 1, 2],
              [0, 2, 4],
              [0, 3, 6]])

# If an element of a is less than 4 → keep it
# Otherwise → replace it with -1

print(np.where(a < 4, a, -1))


   
'''
run:
 
[[ 0  1  2]
 [ 0  2 -1]
 [ 0  3 -1]]
   
'''

 

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