Python Pandas CategoricalIndex - Rename categories with lambda

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To rename categories with Lambda, use the CategoricalIndex rename_categories() method in Pandas.

At first, import the required libraries −

import pandas as pd

CategoricalIndex can only take on a limited, and usually fixed, number of possible values. Set the categories for the categorical using the "categories" parameter. Treat the categorical as ordered using the "ordered" parameter −

catIndex = pd.CategoricalIndex(["P", "Q", "R", "S","P", "Q", "R", "S"], ordered=True, categories=["P", "Q", "R", "S"])

Display the CategoricalIndex −

print("CategoricalIndex...
",catIndex)

Rename categories using rename_categories(). Set the new categories that with use lambda and set lowercase for all the categories −

print("
CategoricalIndex after renaming categories...
",catIndex.rename_categories(lambda a: a.lower()))

Example

Following is the code −

import pandas as pd

# CategoricalIndex can only take on a limited, and usually fixed, number of possible values
# Set the categories for the categorical using the "categories" parameter
# Treat the categorical as ordered using the "ordered" parameter
catIndex = pd.CategoricalIndex(["P", "Q", "R", "S","P", "Q", "R", "S"], ordered=True, categories=["P", "Q", "R", "S"])

# Display the CategoricalIndex
print("CategoricalIndex...
",catIndex) # Get the categories print("
DisplayingCategories from CategoricalIndex...
",catIndex.categories) # Rename categories using rename_categories() # Set the new categories that with use lambda and set lowercase for all the categories print("
CategoricalIndex after renaming categories...
",catIndex.rename_categories(lambda a: a.lower()))

Output

This will produce the following output −

CategoricalIndex...
CategoricalIndex(['P', 'Q', 'R', 'S', 'P', 'Q', 'R', 'S'], categories=['P', 'Q', 'R', 'S'], ordered=True, dtype='category')

DisplayingCategories from CategoricalIndex...
Index(['P', 'Q', 'R', 'S'], dtype='object')

CategoricalIndex after renaming categories...
CategoricalIndex(['p', 'q', 'r', 's', 'p', 'q', 'r', 's'], categories=['p', 'q', 'r', 's'], ordered=True, dtype='category')
raja
Updated on 18-Oct-2021 07:02:14

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