pandas.Categorical.remove_unused_categories — pandas 3.0.0.dev0+2104.ge637b4290d documentation (original) (raw)

Categorical.remove_unused_categories()[source]#

Remove categories which are not used.

This method is useful when working with datasets that undergo dynamic changes where categories may no longer be relevant, allowing to maintain a clean, efficient data structure.

Returns:

Categorical

Categorical with unused categories dropped.

Examples

c = pd.Categorical(["a", "c", "b", "c", "d"]) c ['a', 'c', 'b', 'c', 'd'] Categories (4, object): ['a', 'b', 'c', 'd']

c[2] = "a" c[4] = "c" c ['a', 'c', 'a', 'c', 'c'] Categories (4, object): ['a', 'b', 'c', 'd']

c.remove_unused_categories() ['a', 'c', 'a', 'c', 'c'] Categories (2, object): ['a', 'c']