How to Get the Average of a List in Python

1. Use statistics Library to Get the Average of a List
2. Find the Average of Python List Using sum()/len()
3. Find the Average of Python List Using sum()/float(len()) in Python 2

This tutorial introduces how to find the average of a list in Python. It also lists some example codes to further clarify the concept as the methods have changed from previous versions of Python.

Use statistics Library to Get the Average of a List

If you are using Python 3.4+, you can use newly introduced statistics library. This library contains multiple mathematical functions that can be used straightforwardly. Since we want to calculate the mean of the given list so we will use statistics.mean(list). list is the list of numbers. This function will return the mean (average) of the given list.

The basis example to use this statistics.mean() method is shown below,

import statistics

list = [1, 2, 3, 4, 5, 6]
mean = statistics.mean(list)
print(mean)

Output:

3.5

Find the Average of Python List Using sum()/len()

Using statistics library for calculating the average of a list is not the only option. The average of the list can be calculated by simply dividing the sum of elements by them number of elements.

sum(list) obtains the sum of the given list, and len(list) returns the length of the list.

data = [1, 2, 3, 4, 5, 6]
mean = sum(data) / len(data)
print(mean)

Output:

3.5

Find the Average of Python List Using numpy.mean()

We can also use the numpy.mean() function to get the average of a list in Python. The average is taken over the flattened array by default, otherwise over the specified axis.

However, you need to first install the NumPy module before using it.

The example code to get the average of a list using numpy.mean() is as follows.

import numpy

data = [1, 2, 3, 4, 5, 6]
mean = numpy.mean(data)
print(mean)

Output:

3.5

Find the Average of Python List Using sum()/float(len()) in Python 2

If your Python version is 2.x, then you are not able to use the statistics module and have to use the simple mathematical formula to calculate the average of a given list.

For Python 2 you will need to convert len to a float to get float division. The code will look like this:

data = [1, 2, 3, 4, 5, 6]
mean = sum(data) / float(len(data))
print(mean)

Output:

3.5

If you do not convert len to float, you will not get the floating number but an integer, as shown below.

data = [1, 2, 3, 4, 5, 6]
mean = sum(data) / len(data)
print(mean)

Output:

3