Extracting a 2D numpt array from a 2D numpy array

I'm working with a problem using numpy arrays and I hit a roadblock, basically I have two arrays, one with a 2D numpy array and the other is a 1D numpy which represents some index of the 2D array, what I need is to use pairs of this indexes to extract a 2D numpy array from the original 2D array, I did something, but I'm sure it can be better, so I'm asking for advice. Here is my code:

import numpy as np  import itertools    x = np.arange(25).reshape(5, 5) #Original Array    #x = [[ 0  1  2  3  4]  #     [ 5  6  7  8  9]  #     [10 11 12 13 14]  #     [15 16 17 18 19]  #     [20 21 22 23 24]]    y = np.array([0, 2, 4]) #Indexes    idx = list(itertools.product(y, repeat = 2)) #This create a combination of the indexes to act as my coordinates from the array    #idx = [(0, 0), (0, 2), (0, 4), (2, 0), (2, 2), (2, 4), (4, 0), (4, 2), (4, 4)]    newarray = np.array([x[i] for i in idx]).reshape(3, 3) #This uses the tuples from before to extract the values of the original array    #newarray = [[ 0  2  4]  #            [10 12 14]             #The extracted array  #            [20 22 24]]    

So it works, but I think there is a lot to improve, for example, in the final step I use a list comprehesion and then a numpy array, and then a reshape, also I'm not sure if it's okay to create all the combinations of the index array maybe there is a easier way, so any advice will be appreciated, thank you!

https://stackoverflow.com/questions/67293452/extracting-a-2d-numpt-array-from-a-2d-numpy-array April 28, 2021 at 11:41AM