How to Change Strings to Lowercase in a pandas DataFrame

In this tutorial, you will learn how to lowercase strings in a DataFrame.

df['column_a'] = df['column_a'].str.lower()

Lowercase a DataFrame Column

Suppose, you have the following DataFrame:

         fish  count
0      Salmon    100
1  PufferFish     10
2       Shark      1

You can then use the string method lower() on a DataFrame column as follows:

df['fish'] = df['fish'].str.lower()

print(df['fish'])

The output should look like this:

0        salmon
1    pufferfish
2         shark
Name: fish, dtype: object

That's it! You just changed the strings in a DataFrame column to lowercase.