Creating new numpy matrix from list of rows of existing matrix

Question

I have a 2D numpy array A, and a list x. The elements of x are indices of the rows of A. I want to create a new matrix B, by taking the rows of A as indicated by x. How can I do this?

Ffisegydd · Accepted Answer · 2014-08-14 15:25:55Z

4

You can pass x as an argument when indexing A to create your new matrix B as below. See the docs here.

import numpy as np

A = np.arange(25).reshape((5,5))

x = [1, 2, 4]

B = A[x]

print(B)
# [[ 5  6  7  8  9]
# [10 11 12 13 14]
# [20 21 22 23 24]]

answered Aug 14, 2014 at 15:25

Ffisegydd

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