How to Use the Numpy argsort() Function in Python

09/16/2021

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In this article, you will learn how to use the Numpy argsort() function in Python.

Numpy argsort() Function

The NumPy argsort() function is a powerful tool in Python for sorting an array and returning the indices that would sort the array. Here’s how you can use the argsort() function in Python:

Import the NumPy library:

import numpy as np

Create an array to sort:

arr = np.array([3, 1, 4, 1, 5, 9, 2, 6, 5, 3])

Use the argsort() function to sort the array and return the indices of the sorted elements:

indices = np.argsort(arr)

This will give you an array of indices that would sort the original array:

array([1, 3, 6, 0, 9, 2, 4, 7, 8, 5], dtype=int64)

You can then use these indices to sort the original array or another array in the same way:

sorted_arr = arr[indices]

This will give you the sorted array:

array([1, 1, 2, 3, 3, 4, 5, 5, 6, 9])

Alternatively, you can sort an array in reverse order by specifying the kind parameter:

indices = np.argsort(arr)[::-1]

This will return an array of indices that would sort the original array in descending order.

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