Extracting matrix values from indices using Python

Question

I want to access the elements of matrix A using T to yield a new matrix, Anew with the elements of A using Python. Is there a way to do it?

import numpy as np
A=np.array([[1,2,3],[4,5,6],[7,8,9]])
T=array([[0, 2],
       [1, 1],
       [1, 0]],dtype=int64)

Desired output:

Anew=array([[3],
            [5],
           [4]])

akuiper · Accepted Answer · 2022-02-08 06:28:17Z

1

Use advanced indexing -- the 1st column of T as row index, 2nd column of T as column index:

A[T[:,0], T[:,1]]
# array([3, 5, 4])

answered Feb 8, 2022 at 6:28

akuiper

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Comments

w_sz · Accepted Answer · 2022-02-08 06:28:30Z

0

I'm assuming that the arrays are numpy arrays, in Your case this can be solved with:

A[T.T[0], T.T[1]]

answered Feb 8, 2022 at 6:28

w_sz

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