Replace all the value except for the one a specified index of a numpy matrix with zero

I have the following array

graph2 = [[0, 10, 15, 20],
        [10, 0, 35, 25],
        [15, 35, 0, 30],
        [20, 25, 30, 0]]

I want to replace all to zero except for values at a specific index.
Like Index (1,4), so the 20 at first line i don’t place zero
(4,3) the 30 at fourth list, and (3,1) the 15 in third list

>Solution :

Remember that list index Starts at 1 not at 0. So your list indexes are wrong. I fixed them below

graph2 = [[0, 10, 15, 20],
        [10, 0, 35, 25],
        [15, 35, 0, 30],
        [20, 25, 30, 0]]
skip = [(0, 3), (3, 2), (2,0)]
for i in range(len(graph2)):
    for j in range(len(graph2[i])):
        if (i, j) in skip:
            continue
        else:
            graph2[i][j] = 0
print(graph2)

This should work