How to Find Average of List in Python

Python how to find average of list

To find the average of a list in Python:

  1. Sum up the elements of a list.
  2. Divide the sum by the length of the list.

For example:

grades = [4, 3, 3, 2, 5]

average = sum(grades) / len(grades)

print(f"The average is {average}")

Output:

The average is 3.4

In case you are interested, there are other ways you can compute the average too. Let’s go through these other common approaches.

The For Loop Approach

The most basic way to calculate the average of a list is by using a loop.

In this approach, you sum up the elements of the list using a for loop. Then you divide the sum by the length of the list.

For example:

grades = [4, 3, 3, 2, 5]

sum = 0
for number in grades:
    sum += number

average = sum / len(grades)

print(f"The average is {average}")

Output:

The average is 3.4

Find List Average Using mean() Function

Python has a built-in library called statistics. This library provides basic functionality for mathematics in statistical analysis.

One of the useful functions provided by the statistics library is the mean() function. You can use it to calculate the average for a list.

For example:

from statistics import mean

grades = [4, 3, 3, 2, 5]

average = mean(grades)

print(f"The average is {average}")

Output:

The average is 3.4

Find Average of a List with NumPy mean() Function

NumPy is a commonly used Python library in data science. It provides you with powerful numerical computing tools and multi-dimensional arrays.

This library has also its own implementation of the mean() function.

To use it, first install NumPy by running the following command in your command line window:

from numpy import mean

grades = [4, 3, 3, 2, 5]

average = mean(grades)

print(f"The average is {average}")

Then import the mean function from NumPy library and use it as follows:

The average is 3.4

Find Average of a List Using reduce() Function in Python

Python’s functools library has a function called reduce(). You use this function when computing the average of a list by calculating the sum of the list.

Let’s use reduce() to calculate the average of a list:

from functools import reduce

grades = [4, 3, 3, 2, 5]

average = reduce(lambda x, y: x + y, grades) / len(grades)

print(f"The average is {average}")

Output

The average is 3.4

The reduce() function works by applying an operation on two elements of a list. It remembers the result and applies the operation on the next element and the result. It does this to accumulate a result for the whole list.

The operation in this example is the lambda expression lambda x, y: x + y.

This is nothing but a function that takes two arguments x and y and returns the sum.

When we call reduce() on a list using this lambda, we tell it to sum up the numbers of a list.

Conclusion

Toda you learned five ways to figure out the average of a list in Python.

Thanks for reading. I hope you like it.

Happy coding!

Further Reading

Lambdas in Python

Share on facebook
Facebook
Share on google
Google+
Share on twitter
Twitter
Share on linkedin
LinkedIn
Share on pinterest
Pinterest

Leave a Comment

Your email address will not be published.