Python Pandas CategoricalIndex - Rename categories with dict-like new categories

To rename categories with dict-like new categories, 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. 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...\n",catIndex)

Rename categories. Set the new dict-like categories that will replace the old categories

print("\nCategoricalIndex after renaming categories...\n",catIndex.rename_categories({'p': 5, 'q': 10, 'r': 15, 's': 20}))

Example

Following is the code −

import pandas as pd

# CategoricalIndex can only take on a limited, and usually fixed, number of possible values
# 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...\n",catIndex)

# Get the categories
print("\nDisplaying Categories from CategoricalIndex...\n",catIndex.categories)

# Rename categories
# Set the new dict-like categories that will replace the old categories
print("\nCategoricalIndex after renaming categories...\n",
catIndex.rename_categories({'p': 5, 'q': 10, 'r': 15, 's': 20}))

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')

Displaying Categories from CategoricalIndex...
Index(['p', 'q', 'r', 's'], dtype='object')

CategoricalIndex after renaming categories...
CategoricalIndex([5, 10, 15, 20, 5, 10, 15, 20], categories=[5, 10, 15, 20], ordered=True, dtype='category')