How to find index from raw and column in python

Question

I would like to use in np.put() function, but it requires, target indices, interpreted as integers.

[Problem:] I know raw and column, but now I need to find an index. In my case I have matrix 6 by 6 and I would like to find an index of data[3,3].

heatmap = np.zeros((6,6), dtype=int);
index? = someFuction(heatmap[r,c]);

I have tried to use functions like where(), enumerate() and shape(), but it didn't work.

It should be a very basic solution, but I couldn't find it anywhere online.

Answer 1

You probably want to use np.ravel_multi_index:

import numpy as np
heatmap = np.zeros((6,6), dtype=int)
index = np.ravel_multi_index([[3], [3]], heatmap.shape)
print(index)
>>> [21]