Pandas DataFrame.index

Pandas DataFrame.index

The DataFrame.index property in pandas is used to access or modify the row labels (index) of a DataFrame. The index is critical for identifying rows and organizing data effectively in pandas.

Syntax

The syntax to access or modify the index of a DataFrame is:

DataFrame.index

Here, DataFrame refers to the pandas DataFrame whose index is being accessed or modified.

Examples

Accessing the Index

You can access the index of a DataFrame using the DataFrame.index property:

Python Program

import pandas as pd

data = {
    'Name': ['Arjun', 'Ram', 'Krishna'],
    'Age': [25, 30, 35],
    'City': ['New York', 'Los Angeles', 'Chicago']
}
df = pd.DataFrame(data)

# Accessing the index
print("Index:", df.index)

Output

Index: RangeIndex(start=0, stop=3, step=1)

Modifying the Index

You can assign new row labels to the DataFrame index directly:

Python Program

import pandas as pd

data = {
    'Name': ['Arjun', 'Ram', 'Krishna'],
    'Age': [25, 30, 35],
    'City': ['New York', 'Los Angeles', 'Chicago']
}
df = pd.DataFrame(data)

# Modifying the index
df.index = ['Row1', 'Row2', 'Row3']

# Display the updated DataFrame
print("DataFrame with Modified Index:")
print(df)

# Access the updated index
print("Updated Index:", df.index)

Output

DataFrame with Modified Index:
        Name  Age         City
Row1   Arjun   25     New York
Row2     Ram   30  Los Angeles
Row3 Krishna   35      Chicago

Updated Index: Index(['Row1', 'Row2', 'Row3'], dtype='object')

Accessing Index Attributes

The DataFrame.index property allows you to retrieve attributes such as the values, data type, and name of the index.

Python Program

import pandas as pd

data = {
    'Name': ['Arjun', 'Ram', 'Krishna'],
    'Age': [25, 30, 35],
    'City': ['New York', 'Los Angeles', 'Chicago']
}
df = pd.DataFrame(data)

# Accessing index attributes
print("Index Values:", df.index.values)
print("Index Type:", type(df.index))

Output

Index Values: [0 1 2]
Index Type:

Renaming the Index

You can assign a name to the index for better context and clarity:

Python Program

import pandas as pd

data = {
    'Name': ['Arjun', 'Ram', 'Krishna'],
    'Age': [25, 30, 35],
    'City': ['New York', 'Los Angeles', 'Chicago']
}
df = pd.DataFrame(data)

# Renaming the index
df.index.name = 'RowLabel'

# Display the updated DataFrame
print("DataFrame with Renamed Index:")
print(df)

# Access the index name
print("Index Name:", df.index.name)

Output

DataFrame with Renamed Index:
              Name  Age         City
RowLabel                          
0            Arjun   25     New York
1              Ram   30  Los Angeles
2          Krishna   35      Chicago

Index Name: RowLabel

Summary

In this tutorial, we explored the DataFrame.index property in pandas. We learned how to access the index, modify it, retrieve its attributes, and rename it. The index is an essential part of pandas DataFrames, enabling efficient row identification and data manipulation.

Python Libraries