feat: add Series.to_list (#345)

* feat: add Series.to_list

* add test

docs/api-reference/series.md

@@ -42,6 +42,7 @@
         - sum
         - tail
         - to_frame
+        - to_list
         - to_numpy
         - to_pandas
         - unique

narwhals/_pandas_like/series.py

@@ -180,6 +180,9 @@ def to_frame(self) -> Any:
             self._series.to_frame(), implementation=self._implementation
         )
 
+    def to_list(self) -> Any:
+        return self._series.to_list()
+
     def is_between(
         self, lower_bound: Any, upper_bound: Any, closed: str = "both"
     ) -> PandasSeries:

narwhals/series.py

@@ -301,6 +301,33 @@ def to_frame(self) -> DataFrame:
 
         return DataFrame(self._series.to_frame())
 
+    def to_list(self) -> list[Any]:
+        """
+        Convert to list.
+
+        Examples:
+            >>> import pandas as pd
+            >>> import polars as pl
+            >>> import narwhals as nw
+            >>> s = [1, 2, 3]
+            >>> s_pd = pd.Series(s, name="a")
+            >>> s_pl = pl.Series("a", s)
+
+            We define a library agnostic function:
+
+            >>> @nw.narwhalify
+            ... def func(s_any):
+            ...     return s_any.to_list()
+
+            We can then pass either pandas or Polars to `func`:
+
+            >>> func(s_pd)
+            [1, 2, 3]
+            >>> func(s_pl)
+            [1, 2, 3]
+        """
+        return self._series.to_list()  # type: ignore[no-any-return]
+
     def mean(self) -> Any:
         """
         Reduce this Series to the mean value.

tests/series/to_list_test.py

@@ -0,0 +1,15 @@
+from typing import Any
+
+import pandas as pd
+import polars as pl
+import pytest
+
+import narwhals as nw
+
+data = [1, 2, 3]
+
+
+@pytest.mark.parametrize("constructor", [pd.Series, pl.Series])
+def test_to_list(constructor: Any) -> None:
+    s = nw.from_native(constructor(data), series_only=True)
+    assert s.to_list() == [1, 2, 3]

utils/check_api_reference.py

@@ -145,6 +145,7 @@
     .difference(
         {
             "to_pandas",
+            "to_list",
             "to_numpy",
             "dtype",
             "name",