narwhals.Series.cat

get_categories()

Get unique categories from column.

Examples:

Let's create some series:

>>> import pandas as pd
>>> import polars as pl
>>> import narwhals as nw
>>> from narwhals.typing import IntoSeriesT
>>> data = ["apple", "mango", "mango"]
>>> s_pd = pd.Series(data, dtype="category")
>>> s_pl = pl.Series(data, dtype=pl.Categorical)

We define a dataframe-agnostic function to get unique categories from column 'fruits':

>>> def my_library_agnostic_function(s_native: IntoSeriesT) -> IntoSeriesT:
...     s = nw.from_native(s_native, series_only=True)
...     return s.cat.get_categories().to_native()

We can then pass either pandas or Polars to func:

>>> my_library_agnostic_function(s_pd)
0    apple
1    mango
dtype: object
>>> my_library_agnostic_function(s_pl)
shape: (2,)
Series: '' [str]
[
   "apple"
   "mango"
]