how to set values with same row and column to zero in a numpy ndarray?

Question

I have a numpy ndarray as follows"

x = np.array([[1, 2, 3], [4, 5, 6],[4, 1, 6],[1, 5, 11],[4,3, 4]], np.int32)

i set the value to zero if index with same col, row

rows = x.shape[0]
cols = x.shape[1]
for k in range(0, rows):
    for y in range(0, cols):
        if k==y:
            x[k,y]=0

expected output:

array([[ 0,  2,  3],
       [ 4,  0,  6],
       [ 4,  1,  0],
       [ 1,  5, 11],
       [ 4,  3,  4]])

Is there any simple (pythonic way to achieve the same results)? my actual matrix is very large...

Answer 1

Use np.fill_diagonal :

x = np.array([[1, 2, 3], [4, 5, 6],[4, 1, 6],[1, 5, 11],[4,3, 4]], np.int32)
np.fill_diagonal(x,0)

print(x)
array([[ 0,  2,  3],
       [ 4,  0,  6],
       [ 4,  1,  0],
       [ 1,  5, 11],
       [ 4,  3,  4]], dtype=int32)