'typing' pandas-like, adding comment

Author: FBruzzesi

narwhals/_dask/expr.py

@@ -85,7 +85,7 @@ def __narwhals_namespace__(self) -> DaskNamespace:  # pragma: no cover
     def broadcast(self, kind: Literal[ExprKind.AGGREGATION, ExprKind.LITERAL]) -> Self:
         def func(df: DaskLazyFrame) -> list[dx.Series]:
             # result.loc[0][0] is a workaround for dask~<=2024.10.0/dask_expr~<=1.1.16
-            #   that raised a KeyErrror for result[0] during collection.
+            #   that raised a KeyError for result[0] during collection.
             return [result.loc[0][0] for result in self(df)]
 
         return self.__class__(

narwhals/_pandas_like/series.py

@@ -490,13 +490,14 @@ def __rtruediv__(self, other: Any) -> Self:
 
     def __floordiv__(self, other: Any) -> Self:
         native, other = align_and_extract_native(self, other)
+        native = cast("pd.Series[Any]", native)
         native_cls = type(native)
         other_is_series = isinstance(other, native_cls)
 
         safe_div_mask = other != 0
 
-        if ((not other_is_series) and safe_div_mask is True) or (
-            other_is_series and safe_div_mask.all()
+        if (other_is_series and safe_div_mask.all()) or (
+            (not other_is_series) and safe_div_mask is True
         ):  # fast path, there are no zero's in other
             result_native = native // other
         else:
@@ -511,10 +512,19 @@ def __floordiv__(self, other: Any) -> Self:
 
                 from narwhals._arrow.utils import floordiv_compat
 
-                native_pa = native.array._pa_array
-                other_pa = other.array._pa_array if other_is_series else pa.scalar(other)
+                native_pa = native.array._pa_array  # type: ignore[attr-defined]
+                other_pa = (
+                    other.array._pa_array  # pyright: ignore[reportAttributeAccessIssue]
+                    if other_is_series
+                    else pa.scalar(other, type=pa.int64())
+                    # TODO(FBruzzesi): How can be improve on pinning down the type?
+                )
                 result_array = floordiv_compat(native_pa, other_pa)
             else:
+                # Note that we use numpy/cupy where instead of pandas-like Series.where
+                # to avoid handling broadcasting for scalars.
+                # np.where(True, x, y) -> x, np.where(False, x, y) -> y
+                # x.where(True, y) -> raises an exception due to shape mismatch
                 result_array = array_funcs.where(
                     safe_div_mask,
                     native // other,

tests/stable_v1_dependencies_test.py

@@ -6,7 +6,7 @@
 import pandas as pd
 
 
-def test_stable_v1_dependenies_import() -> None:
+def test_stable_v1_dependencies_import() -> None:
     # https://github.com/bokeh/bokeh/pull/14530#issuecomment-2984474111
     # Note: for some reason, this test needs to be in its own file to reproduce
     # the error observed in Bokeh's CI. Please don't move this test to