To add new categories, use the CategoricalIndex add_categories() method in Pandas. At first, import the required libraries −
import pandas as pd
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...\n",catIndex)
Add new categories using add_categories(). Set the new categories as a parameter. The new categories will be included at the last/highest place in the categories −
print("\nCategoricalIndex after adding new categories...\n",catIndex.add_categories(["a", "b", "c", "d"]))
Example
Following is the code −
import pandas as pd # CategoricalIndex can only take on a limited, and usually fixed, number of possible values (categories # 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...\n",catIndex) # Get the categories print("\nDisplayingCategories from CategoricalIndex...\n",catIndex.categories) # Add new categories using add_categories() # Set the new categories as a parameter # The new categories will be included at the last/highest place in the categories print("\nCategoricalIndex after adding new categories...\n",catIndex.add_categories(["a", "b", "c", "d"]))
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 adding new categories... CategoricalIndex(['p', 'q', 'r', 's', 'p', 'q', 'r', 's'], categories=['p', 'q', 'r', 's', 'a', 'b', 'c', 'd'], ordered=True, dtype='category')