how to get the index of numpy.random.choice? - python

Question

Is it possible to modify the numpy.random.choice function in order to make it return the index of the chosen element? Basically, I want to create a list and select elements ran

Answer 1

Based on your comment:

The sample is already a. I want to work directly with a so that I can control how many elements are still left and perform other operations with a. – HappyPy

it sounds to me like you're interested in working with a after n randomly selected elements are removed. Instead, why not work with N = len(a) - n randomly selected elements from a? Since you want them to still be in the original order, you can select from indices like in @CTZhu's answer, but then sort them and grab from the original list:

import numpy as np
n = 3 #number to 'remove'
a = np.array([1,4,1,3,3,2,1,4])
i = np.random.choice(np.arange(a.size), a.size-n, replace=False)
i.sort()
a[i]
#array([1, 4, 1, 3, 1])

So now you can save that as a again:

a = a[i]

and work with a with n elements removed.