I would like to know if there exists a similar way of doing this (Mathematica) in Python: Mathematica
I have tried it in Python and it does not work. I have also tried it with numpy.put() or with simple 2 for loops. This 2 ways work properly but I find them very time consuming with larger matrices (3000×3000 elements for example).
Described problem in Python,
import numpy as np
a = np.arange(0, 25, 1).reshape(5, 5)
b = np.arange(100, 500, 100).reshape(2, 2)
p = np.array([0, 3])
a[p][:, p] = b
which outputs non-changed matrix a: Python
Perhaps you are looking for this:
a[p[...,None], p] = b
Array a after the above assignment looks like this:
[[100 1 2 200 4]
[ 5 6 7 8 9]
[ 10 11 12 13 14]
[300 16 17 400 19]
[ 20 21 22 23 24]]
As documented in Integer Array Indexing, the two integer index arrays will be broadcasted together, and iterated together, which effectively indexes the locations a[0,0], a[0,3], a[3,0], and a[3,3]. The assignment statement would then perform an element-wise assignment at these locations of a, using the respective element-values from RHS.