How to Add Numbers in a Csv File Using Python

When working with CSV files in Python, adding numbers in the CSV file is a common requirement. This article will guide you through the process of adding numbers within a CSV file. Whether you're new to data analysis or an experienced practitioner, understanding this skill is vital for efficient data management

CSV (Comma-Separated Values): A common file format for storing tabular data in plain text format, where each line represents a row, and values within a row are separated by commas.

Add Numbers in a CSV File Using Python

Below are the code examples of how to add numbers in a CSV file in Python:

Example 1: Add Values of All Columns of the CSV File

The file structure consists of two files: "main.py" and "numbers.csv".

numbers.csv

A,B
1,2
3,4
5,6

In this example, below code reads a CSV file called "numbers.csv", adds the values from two columns, and saves the results to a new CSV file called "numbers_updated.csv". It iterates through each row of the data, extracts values from columns A and B, performs addition, handles non-numeric values, and writes the updated data back to the new CSV file.

main.py

Output

Addition completed and updated CSV file created successfully.

numbers_updated.csv

A,B,
1,2,3
3,4,7
5,6,11

Example 2: Add Values of Specific Column of CSV file

The file structure consists of two files: "main.py" and "input.csv".

input.csv

Name, Age, Score
John, 25, 85.5
Amy, 31, 92.2
Sam, 28, 78.9

In below example, we are using csv.reader to read the CSV file (eg. input.csv) and store its contents into a suitable data structure, such as a list of lists or a Pandas DataFrame. Then, Iterate over the data and sum up the numbers using the Decimal class for precision. Assuming the numbers are in a specific column, we can access that column by its index.

Output

Invalid value in row: ['Name', ' Age', ' Score']
Total: 256.6

output.csv

Total
256.6