How to Get the Variance of a List in Python?

Hi Dev,

This article is focused on How to Get the Variance of a List in Python. This article goes in detailed on Python calculate variance without numpy. I explained simply step by step Find Variance Using Python Example. In this article, we will implement a Python Program to Calculate the Variance. Follow bellow tutorial step of NumPy Variance Function in Python.

Python program to find variance; In this tutorial, you will learn how to find or calculate the variance in python using numpy.

so let's see following examples with output:

Example 1: Write a program to calculate variance in python

import numpy as np

 
dataset= [21, 11, 19, 18, 29, 46]

 
variance= np.var(dataset)

 
print(variance)

Output:

124.66666666666667

Example 2: Python calculate variance without numpy

#define a function, to calculate variance
def variance(X):
    mean = sum(X)/len(X)
    tot = 0.0
    for x in X:
        tot = tot + (x - mean)**2
    return tot/len(X)

 
# call the function with data set
x = [1, 2, 3, 4, 5, 6, 7, 8] 
print("variance is: ", variance(x))

 
y = [1, 2, 3, -4, -5, -6, -7] 
print("variance is: ", variance(y))

 
z = [10, -20, 30, -40, 50, -60, 70] 
print("variance is: ", variance(z))

Output:

variance is:  5.25
variance is:  14.775510204081632
variance is:  1967.3469387755104