Categoricals ============ ``Categoricals`` enable compact storage of objects (strings). Sure they come with a learning curve, but they can be very useful. A categorical column is essentially a map of an integer (called ``cat_codes``) to each string, which enables repeated rows of strings to be stored with less memory. The user sees the string they expect, but the memory overhead is reduced. The pandera_utils package allows you to add additional maps to each category. Typical use cases include adding a label or description. .. literalinclude:: ../../../assets/category_schema.yaml :language: yaml The ``isin`` check is used to define the categories that are allowed in the column, in the case that the ``add_all_categories`` key is not set to false. If the key is set to false, only categories present in the loaded data will define the allowable categories. For more information see the `pandas documentation `_.