How to change the values of a DataFrame column with Pandas using Python

7-Day Challenge

Land Your First Data Science Job

A proven roadmap to prepare for $75K+ entry-level data roles. Perfect for Data Scientist ready to level up their career.

Build portfolios that hiring managers love
Master the Python and SQL essentials to be industry-ready
Practice with real interview questions from tech companies
Access to the $100k/y Data Scientist Cheatsheet

Join thousands of developers who transformed their careers through our challenge. Unsubscribe anytime.

By default you can edit the value of a Pandas Series using the DataFrame.apply() method.

This method can perform row by row or column by column operations.

And you can either work with lambda functions or apply a method directly.

Here is the code

# To work with dataframes
import pandas as pd

# We create a sample dataframe
df = pd.DataFrame({"col1" : [0, 10, 3, 11, 3, 12]})

# How to change the values of a DataFrame Series
df["col1"] = df["col1"].apply(lambda x: x + 2)

print(df["col1"])

def multiply_by_two(x):
    """Multiplies x by two"""
    return x * 2

# Now we apply the method by specifying the method
# directly instead of a lambda
df["col1"] = df["col1"].apply(multiply_by_two)

print(df["col1"])

def multiply_by_n(x, n):
    """Multiplies x by n"""
    return x * n

# Now we pass a method along with an argument required 
# by the multiply_by_n method
df["col1"] = df["col1"].apply(multiply_by_n, n=2)

print(df["col1"])

Here you are! You now know how to change the values of a DataFrame Column with Pandas using Python!

More on DataFrames

If you want to know more about DataFrame and Pandas. Check out the other articles I wrote on the topic, just here :

Pandas - The Python You Need
We gathered the only Python essentials that you will probably ever need.
7-Day Challenge

Land Your First Data Science Job

A proven roadmap to prepare for $75K+ entry-level data roles. Perfect for Data Scientist ready to level up their career.

Build portfolios that hiring managers love
Master the Python and SQL essentials to be industry-ready
Practice with real interview questions from tech companies
Access to the $100k/y Data Scientist Cheatsheet

Join thousands of developers who transformed their careers through our challenge. Unsubscribe anytime.

Free Newsletter

Master Data Science in Days, Not Months 🚀

Skip the theoretical rabbit holes. Get practical data science skills delivered in bite-sized lessons – Approach used by real data scientist. Not bookworms. 📚

Weekly simple and practical lessons
Access to ready to use code examples
Skip the math, focus on results
Learn while drinking your coffee

By subscribing, you agree to receive our newsletter. You can unsubscribe at any time.