[Python] How to Do Math with Lists [average]

This article shows how to do math with lists.

The four arithmetic operations with elements of a List

In the beginning, I show the basics of the four arithmetic operations with elements of a List.

These are the arithmetic operators in Python.

Modulus: returns the remainder when first operand is divided by the second

Power : Returns first raised to power second

Addition of elements in a list [ using "for loop" ]

I show how to calculate addition of elements in a list using "for loop".

Here is an example code.

num_list = [1, 2, 3, 4, 5]
tmp = 0
sum_num = 0

for i in range(len(num_list)):
    tmp = num_list[i] + tmp

print(tmp)
# 15

The elements in the list are added by the following repetition.

i = 0 : tmp = num_list[0] + tmp = 1 + 0

i = 1 : tmp = num_list[1] + tmp = 2 + 1

Addition of elements in a list [ using "sum() function" ]

Addition of elements in a list can be easily calculated by using the sum( ) function.

Here is an example code.

num_list = [1, 2, 3, 4, 5]

print(sum(num_list))
# 15

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Average of elements of a List

I show how to calculate average of elements in a list.

Two methods are described in this article.

• Using "sum() and len() functions"
• Using "statistics" of library

Average of elements in a list [ using "sum() and len() functions" ]

I show how to calculate average of elements in a list by using "sum() and len() functions".

Here is an example code.

num_list = [1, 2, 3, 4, 5]

mean = sum(num_list)/len(num_list)
print(mean)
# 3.0

Average of elements in a list [ using "statistics" of library]

Average of elements in a list can be easily calculated by using "statistics" of library.

Here is an example code.

import statistics

num_list = [1, 2, 3, 4, 5]

mean = statistics.mean(num_list)
print(mean)
# 3

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How to calculate the elements between two lists using "for loop"

In the following sections, I will show you how to calculate the elements between the two lists.

First, I will show you how to calculate using "for loop".

Here is an example code.

num_list_1 = [1, 2, 3, 4, 5]
num_list_2 = [10, 20, 30, 40, 50]
tmp = 0
num_list_3 = []

for i in range(len(num_list_1)):
    tmp = num_list_1[i] + num_list_2[i]
    num_list_3.append(tmp)

print(num_list_3)
# [11, 22, 33, 44, 55]

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How to calculate the elements between two lists using zip( ) function

I show how to calculate the elements between two lists using zip( ) function.

The elements of multiple lists can be retrieved at once by using zip( ) function.

Here is an sample code.

num_list_1 = [1, 2, 3, 4, 5]
num_list_2 = [10, 20, 30, 40, 50]

num_list_3 = [x + y for x, y in zip(num_list_1, num_list_2)]

print(num_list_3)
# [11, 22, 33, 44, 55]

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How to calculate the elements between two lists using map( ) function and lambda

I show how to calculate the elements between two lists using map( ) function and lambda.

The map() function can be used to apply the processing of a particular function to all elements of a list.

Lambda is used to define functions.

Here is an example code.

num_list_1 = [1, 2, 3, 4, 5]
num_list_2 = [10, 20, 30, 40, 50]

num_list_3 = [x + y for x, y in zip(num_list_1, num_list_2)]

print(num_list_3)
# [11, 22, 33, 44, 55]

By the way, the following article describes how to use map( ) function and lambda.

How to use map() Function.
How to use Lambda Function.

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