• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar

The Programming Expert

Solving All of Your Programming Headaches

  • HTML
  • JavaScript
  • jQuery
  • PHP
  • Python
  • SAS
  • Ruby
  • About
You are here: Home / Python / Using pandas to_csv() Function to Append to Existing CSV File

Using pandas to_csv() Function to Append to Existing CSV File

October 19, 2022 Leave a Comment

To append to an existing CSV file with pandas, you can use the to_csv() function and pass “mode=’a'” to specify you want to append to the CSV file.

df.to_csv('example.csv', mode='a', index=False, header=False)

When outputting data to different types of files, the ability to append to a file easily is valuable.

One such case is if you want to append to an existing CSV file in Python with pandas.

To write a pandas DataFrame to a CSV, you can use the to_csv() function. If you want to add data to a CSV file, you can use the same function and pass some additional arguments.

For adding rows to an existing CSV file, you should pass “mode=’a'” to specify you want to append to the CSV. You should also pass “header=False” because the CSV will most likely already have a header.

One final argument you can pass a value to is the ‘index’ argument. Depending on whether or not the existing CSV already has an index or not, you will want to set this to True or False.

If you don’t use the “index” argument, it’s possible that your output will not be suitable for downstream processes which depend on the CSV file.

Below is an example showing you how you can use to_csv() to append to an existing CSV file with pandas in Python.

df.to_csv('example.csv', mode='a', index=False, header=False)

Hopefully this article has been useful for you to learn how to add to an existing CSV file with pandas.

Other Articles You'll Also Like:

  • 1.  How to Ask a Question in Python
  • 2.  Convert False to 0 in Python
  • 3.  Get the Count of NaN in pandas Using Python
  • 4.  Count Spaces in String in Python
  • 5.  Why Dictionaries Can’t Have Duplicate Keys in Python
  • 6.  Print Time Elapsed in Python
  • 7.  Find Quotient and Remainder After Division in Python
  • 8.  How to Hide Turtle in Python with hideturtle() Function
  • 9.  Remove Leading Zeros from String with lstrip() in Python
  • 10.  Remove Every Nth Element from List in Python

About The Programming Expert

The Programming Expert is a compilation of a programmer’s findings in the world of software development, website creation, and automation of processes.

Programming allows us to create amazing applications which make our work more efficient, repeatable and accurate.

At the end of the day, we want to be able to just push a button and let the code do it’s magic.

You can read more about us on our about page.

Reader Interactions

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar

About The Programming Expert

the programming expert main image

Welcome to The Programming Expert. We are a group of US-based programming professionals who have helped companies build, maintain, and improve everything from simple websites to large-scale projects.

We built The Programming Expert to help you solve your programming problems with useful coding methods and functions in various programming languages.

Search

Learn Coding from Experts on Udemy

Looking to boost your skills and learn how to become a programming expert?

Check out the links below to view Udemy courses for learning to program in the following languages:

Copyright © 2023 · The Programming Expert · About · Privacy Policy