Python Pandas - Set the categories of the CategoricalIndex to be unordered

To set the categories of the CategoricalIndex to be unordered, use the as_unordered() method in Pandas. This method converts an ordered categorical index to an unordered one.

Creating an Ordered CategoricalIndex

First, let's create an ordered CategoricalIndex using the ordered=True parameter ?

import pandas as pd

# Create an ordered CategoricalIndex
catIndex = pd.CategoricalIndex(["p", "q", "r", "s", "p", "q", "r", "s"], 
                               ordered=True, 
                               categories=["p", "q", "r", "s"])

print("Original CategoricalIndex...")
print(catIndex)
print(f"Is ordered: {catIndex.ordered}")

Original CategoricalIndex...
CategoricalIndex(['p', 'q', 'r', 's', 'p', 'q', 'r', 's'], categories=['p', 'q', 'r', 's'], ordered=True, dtype='category')
Is ordered: True

Converting to Unordered Using as_unordered()

Now, use the as_unordered() method to convert the ordered categorical to unordered ?

import pandas as pd

# Create an ordered CategoricalIndex
catIndex = pd.CategoricalIndex(["p", "q", "r", "s", "p", "q", "r", "s"], 
                               ordered=True, 
                               categories=["p", "q", "r", "s"])

# Convert to unordered
unordered_catIndex = catIndex.as_unordered()

print("Original (ordered):")
print(catIndex)
print(f"Is ordered: {catIndex.ordered}")

print("\nAfter as_unordered():")
print(unordered_catIndex)
print(f"Is ordered: {unordered_catIndex.ordered}")

Original (ordered):
CategoricalIndex(['p', 'q', 'r', 's', 'p', 'q', 'r', 's'], categories=['p', 'q', 'r', 's'], ordered=True, dtype='category')
Is ordered: True

After as_unordered():
CategoricalIndex(['p', 'q', 'r', 's', 'p', 'q', 'r', 's'], categories=['p', 'q', 'r', 's'], ordered=False, dtype='category')
Is ordered: False

Complete Example

Here's a comprehensive example showing the categories and the conversion process ?

import pandas as pd

# Create an ordered CategoricalIndex
catIndex = pd.CategoricalIndex(["p", "q", "r", "s", "p", "q", "r", "s"], 
                               ordered=True, 
                               categories=["p", "q", "r", "s"])

# Display the original CategoricalIndex
print("CategoricalIndex...")
print(catIndex)

# Display the categories
print("\nDisplaying Categories from CategoricalIndex...")
print(catIndex.categories)

# Convert to unordered
print("\nCategoricalIndex unordered...")
print(catIndex.as_unordered())

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 unordered...
CategoricalIndex(['p', 'q', 'r', 's', 'p', 'q', 'r', 's'], categories=['p', 'q', 'r', 's'], ordered=False, dtype='category')

Key Points

The as_unordered() method:

• Returns a new CategoricalIndex with ordered=False
• Preserves all categories and their values
• Only changes the ordering property of the categorical data
• Does not modify the original CategoricalIndex

Conclusion

Use as_unordered() to convert an ordered CategoricalIndex to unordered. This method preserves all data and categories while removing the ordering property.