What Is Category Data Type in Python?


Scott Campbell

The category data type in Python is a powerful tool that allows you to efficiently manage and analyze categorical or discrete data. Categorical data consists of values that belong to a specific set of categories, such as colors, types of animals, or even survey responses. In this tutorial, we will explore the category data type in Python and learn how to leverage its benefits.

What is Categorical Data?

Categorical data represents information that can be divided into specific groups or categories. Unlike numerical or continuous data, which can take on any value within a range, categorical data has a limited number of distinct values.

For example, if we have a dataset containing information about the color of fruits, the categories could include “red,” “green,” and “yellow. “

The Need for Category Data Type

Traditional Python data types like strings and integers are not always the most efficient way to handle categorical data. When working with large datasets or performing complex operations on categorical variables, using the category data type can significantly improve performance and memory usage.

By default, Python represents categorical variables as objects, which consume more memory compared to the category data type. The category data type is an optimized implementation provided by pandas, a popular library for data manipulation and analysis in Python.

Benefits of Category Data Type

Using the category data type offers several advantages:

  • Improved Performance: Since the category data type uses integer-based codes internally instead of storing each unique value as a string or object, it reduces memory usage and speeds up operations like sorting and grouping.
  • Easier Data Management: The category data type provides built-in functionalities for handling missing values (NaN), renaming categories, reordering categories based on logical order or frequency, and even merging categories.
  • Reduced Storage Space: Categorical variables tend to have a limited number of unique values. By using the category data type, you can store these values more efficiently, resulting in reduced storage space requirements.

Using Category Data Type in Python

To use the category data type, you need to import the pandas library:

import pandas as pd

Now, let’s assume we have a dataset with a column named “animal” that contains categorical values:

data = {'animal': ['cat', 'dog', 'cat', 'dog', 'dog', 'cat']}
df = pd.DataFrame(data)

To convert this column to the category data type, we can use the astype() method:

df['animal'] = df['animal'].astype('category')

You can also specify additional parameters while converting to the category data type. For example, if you want to set a specific order for the categories:

df['animal'] = df['animal'].astype('category', categories=['dog', 'cat'], ordered=True)


The category data type in Python is a valuable tool for efficiently managing and analyzing categorical data. By leveraging its benefits like improved performance and reduced memory usage, you can enhance your data manipulation and analysis workflows. Remember to import the pandas library and use the astype() method to convert your categorical variables to the category data type.

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