How to Rename Index in pandas: Simple Guide with Examples

To rename the index in pandas, use the rename() method on the DataFrame with the index parameter specifying a mapping of old to new index labels. You can also rename the index axis label using df.index.name.

Syntax

The main way to rename index labels in pandas is using the rename() method with the index argument. You pass a dictionary mapping old index names to new ones.

• df.rename(index={'old_label': 'new_label'}): Renames specific index labels.
• df.index.name = 'new_name': Changes the name of the index axis (the label shown above the index).

python

df.rename(index={'old_label': 'new_label'}, inplace=True)
df.index.name = 'new_index_name'

Example

This example shows how to rename specific index labels and how to set a new name for the index axis.

python

import pandas as pd

# Create a sample DataFrame
data = {'A': [10, 20, 30], 'B': [100, 200, 300]}
df = pd.DataFrame(data, index=['x', 'y', 'z'])

# Rename index label 'x' to 'alpha' and 'z' to 'gamma'
df.rename(index={'x': 'alpha', 'z': 'gamma'}, inplace=True)

# Rename the index axis name
df.index.name = 'letters'

print(df)

Output

         A    B
letters         
alpha   10  100
y       20  200
gamma   30  300

Common Pitfalls

One common mistake is forgetting to use inplace=True or to assign the result back to a variable, so the rename does not persist.

Another is confusing renaming index labels with renaming columns.

python

import pandas as pd

df = pd.DataFrame({'A': [1, 2]}, index=['a', 'b'])

# Wrong: rename without inplace or assignment
df.rename(index={'a': 'alpha'})
print(df)

# Right: use inplace=True or assign
df.rename(index={'a': 'alpha'}, inplace=True)
print(df)

Output

   A
a  1
b  2
   A
alpha  1
b      2

Quick Reference

Action	Code Example	Description
Rename specific index labels	df.rename(index={'old': 'new'}, inplace=True)	Change one or more index labels.
Rename index axis name	df.index.name = 'new_name'	Set or change the name of the index axis.
Rename columns (for comparison)	df.rename(columns={'old': 'new'}, inplace=True)	Change column names, not index.

Key Takeaways

Use df.rename(index={old:new}, inplace=True) to rename index labels.

Set df.index.name to rename the index axis label.

Always use inplace=True or assign the result to keep changes.

Renaming index labels is different from renaming columns.

Check your DataFrame after renaming to confirm changes.