Find the index of the k smallest values of a NumPy array

Learn, how to find the index of the k smallest values of a NumPy array in Python? By Pranit Sharma Last updated : October 09, 2023

NumPy is an abbreviated form of Numerical Python. It is used for different types of scientific operations in python. Numpy is a vast library in python which is used for almost every kind of scientific or mathematical operation. It is itself an array which is a collection of various methods and functions for processing the arrays.

Problem statement

Suppose we are given a numpy array and also a specific integer value up to which we need to find the smallest values of this array.

NumPy Array - Finding the index of the k smallest values

For this purpose, we will use numpy.argpartition() method that states that the kth element is in a sorted position and all smaller elements will be moved before it. Thus the first k elements will be the k-smallest elements.

Let us understand with the help of an example,

Python program to find the index of the k smallest values of a NumPy array

# Import numpy
import numpy as np

# Import pandas
import pandas as pd

# Creating an array
arr = np.array([1,2,-45,2,-6,3,-7,4,-2])

# Display array
print("Original array:\n",arr,"\n")

# Defining value for k
k = 3

# Finding index of kth smallest values
ind = np.argpartition(arr, k)

# Display result
print("Result:\n",ind,"\n")