CategoricalIndex.rename_categories(self, *args, **kwargs)[source]

Rename categories.

new_categorieslist-like, dict-like or callable

New categories which will replace old categories.

  • list-like: all items must be unique and the number of items in the new categories must match the existing number of categories.

  • dict-like: specifies a mapping from old categories to new. Categories not contained in the mapping are passed through and extra categories in the mapping are ignored.

New in version 0.21.0..

  • callable : a callable that is called on all items in the old categories and whose return values comprise the new categories.

New in version 0.23.0..

inplacebool, default False

Whether or not to rename the categories inplace or return a copy of this categorical with renamed categories.

catCategorical or None

With inplace=False, the new categorical is returned. With inplace=True, there is no return value.


If new categories are list-like and do not have the same number of items than the current categories or do not validate as categories


>>> c = pd.Categorical(['a', 'a', 'b'])
>>> c.rename_categories([0, 1])
[0, 0, 1]
Categories (2, int64): [0, 1]

For dict-like new_categories, extra keys are ignored and categories not in the dictionary are passed through

>>> c.rename_categories({'a': 'A', 'c': 'C'})
[A, A, b]
Categories (2, object): [A, b]

You may also provide a callable to create the new categories

>>> c.rename_categories(lambda x: x.upper())
[A, A, B]
Categories (2, object): [A, B]