Pandas >> How to Rename Column and Index

Table of Contents

In this article, we will talk about how to rename column name or Index in DataFrame.

Firstly, we prepare data for demonstration.

Preparing data

import pandas as pd

df = pd.DataFrame({
    "name": ["Kevin", "Jack", "Mary", "Bob", "Robert", "Amy"],
    "score": [80, 90, 95, 93, 88, 81],
    "class": ["A", "B", "A", "A", "B", "B"]
}, index=["K", "J", "M", "B", "R", "A"])

df

Result

Rename column names

We can assign a list of new column names to columns attribute of DataFrame.
Attention: The column names of original DataFrame will be changed permanently.

df.columns = ["name_1", "score_1", "class_1"]
df

Result

We can also use rename method of DataFrame to change part of column names. Attention: In this way, the column names of original DataFrame will not be changed and a new DataFrame with new column names will be returned. If you want to change original column names directly, you can specify inplace=True. DataFrame.rename(columns={<OLD COLUMN NAME>: <NEW COLUMN NAME>})

# Original DataFrame column names will not be changed
df.rename(columns={"name_1": "name_2", "score_1": "score_2"})

# Original DataFrame column names will be changed
df.rename(columns={"name_1": "name_2", "score_1": "score_2"}, inplace=True)

Result

Rename Index

We can also use rename method to change part or all of Index. Attention: In this way, the Index of original DataFrame will not be changed and a new DataFrame with new Index will be returned. If you want to change original Index directly, you can specify inplace=True. DataFrame.rename(index={<OLD Index NAME>: <NEW Index NAME>})

# Original DataFrame index will not be changed
df.rename(index={"K": "KV", "R": "RB"})

# Original DataFrame index will be changed
df.rename(index={"K": "KV", "R": "RB"}, inplace=True)

Result

Resetting Index

We can also use set_index method to reset index of DataFrame. Attention: In this way, the Index of original DataFrame will not be changed and a new DataFrame with new Index will be returned. If you want to change original Index directly, you can specify inplace=True. DataFrame.rename(index={<OLD Index NAME>: <NEW Index NAME>})

# Original DataFrame index will not be changed
df.set_index("name")

# Original DataFrame index will be changed
df.set_index("name", inplace=True)

Result
new index
↓↓↓

If we want to change the current index to a column, we can use reset_index method. A numeric index will be created as new Index.

# Original DataFrame index will not be changed
df.reset_index()

# Original DataFrame index will be changed
df.reset_index(inplace=True)

Result
new index (ascending numeric index)
↓↓↓

We can use pandas method chaining (reset_index().set_index()) to change index without data loss.

# Original DataFrame index will not be changed
df.reset_index().set_index("name")

Result
new index
↓↓↓