chore: use __narwhals_namespace__ more (#1658)

narwhals/_arrow/dataframe.py

@@ -504,7 +504,7 @@ def filter(self: Self, *predicates: IntoArrowExpr, **constraints: Any) -> Self:
                     predicates, (plx.col(name) == v for name, v in constraints.items())
                 )
             )
-            # Safety: all_horizontal's expression only returns a single column.
+            # `[0]` is safe as all_horizontal's expression only returns a single column
             mask = expr._call(self)[0]._native_series
         return self._from_native_frame(self._native_frame.filter(mask))
 

narwhals/_arrow/namespace.py

@@ -461,11 +461,9 @@ def __call__(self: Self, df: ArrowDataFrame) -> Sequence[ArrowSeries]:
         import pyarrow as pa
         import pyarrow.compute as pc
 
-        from narwhals._arrow.namespace import ArrowNamespace
         from narwhals._expression_parsing import parse_into_expr
 
-        plx = ArrowNamespace(backend_version=self._backend_version, version=self._version)
-
+        plx = df.__narwhals_namespace__()
         condition = parse_into_expr(self._condition, namespace=plx)(df)[0]
         try:
             value_series = parse_into_expr(self._then_value, namespace=plx)(df)[0]

narwhals/_dask/dataframe.py

@@ -105,13 +105,11 @@ def filter(self, *predicates: DaskExpr, **constraints: Any) -> Self:
             )
             raise NotImplementedError(msg)
 
-        from narwhals._dask.namespace import DaskNamespace
-
-        plx = DaskNamespace(backend_version=self._backend_version, version=self._version)
+        plx = self.__narwhals_namespace__()
         expr = plx.all_horizontal(
             *chain(predicates, (plx.col(name) == v for name, v in constraints.items()))
         )
-        # Safety: all_horizontal's expression only returns a single column.
+        # `[0]` is safe as all_horizontal's expression only returns a single column
         mask = expr._call(self)[0]
         return self._from_native_frame(self._native_frame.loc[mask])
 

narwhals/_dask/namespace.py

@@ -416,11 +416,9 @@ def __init__(
         self._version = version
 
     def __call__(self, df: DaskLazyFrame) -> Sequence[dask_expr.Series]:
-        from narwhals._dask.namespace import DaskNamespace
         from narwhals._expression_parsing import parse_into_expr
 
-        plx = DaskNamespace(backend_version=self._backend_version, version=self._version)
-
+        plx = df.__narwhals_namespace__()
         condition = parse_into_expr(self._condition, namespace=plx)(df)[0]
         condition = cast("dask_expr.Series", condition)
         try:

narwhals/_pandas_like/dataframe.py

@@ -412,7 +412,7 @@ def filter(self, *predicates: IntoPandasLikeExpr, **constraints: Any) -> Self:
                     predicates, (plx.col(name) == v for name, v in constraints.items())
                 )
             )
-            # Safety: all_horizontal's expression only returns a single column.
+            # `[0]` is safe as all_horizontal's expression only returns a single column
             mask = expr._call(self)[0]
             _mask = validate_dataframe_comparand(self._native_frame.index, mask)
         return self._from_native_frame(self._native_frame.loc[_mask])
@@ -1006,7 +1006,6 @@ def explode(self: Self, columns: str | Sequence[str], *more_columns: str) -> Sel
             ]
 
             plx = self.__native_namespace__()
-
             return self._from_native_frame(
                 plx.concat([exploded_frame, *exploded_series], axis=1)[original_columns]
             )

narwhals/_pandas_like/namespace.py

@@ -503,15 +503,9 @@ def __init__(
 
     def __call__(self, df: PandasLikeDataFrame) -> Sequence[PandasLikeSeries]:
         from narwhals._expression_parsing import parse_into_expr
-        from narwhals._pandas_like.namespace import PandasLikeNamespace
         from narwhals._pandas_like.utils import broadcast_align_and_extract_native
 
-        plx = PandasLikeNamespace(
-            implementation=self._implementation,
-            backend_version=self._backend_version,
-            version=self._version,
-        )
-
+        plx = df.__narwhals_namespace__()
         condition = parse_into_expr(self._condition, namespace=plx)(df)[0]
         try:
             value_series = parse_into_expr(self._then_value, namespace=plx)(df)[0]

narwhals/_spark_like/dataframe.py

@@ -104,20 +104,16 @@ def select(
         return self._from_native_frame(self._native_frame.select(*new_columns_list))
 
     def filter(self, *predicates: SparkLikeExpr) -> Self:
-        from narwhals._spark_like.namespace import SparkLikeNamespace
-
         if (
             len(predicates) == 1
             and isinstance(predicates[0], list)
             and all(isinstance(x, bool) for x in predicates[0])
         ):
             msg = "`LazyFrame.filter` is not supported for PySpark backend with boolean masks."
             raise NotImplementedError(msg)
-        plx = SparkLikeNamespace(
-            backend_version=self._backend_version, version=self._version
-        )
+        plx = self.__narwhals_namespace__()
         expr = plx.all_horizontal(*predicates)
-        # Safety: all_horizontal's expression only returns a single column.
+        # `[0]` is safe as all_horizontal's expression only returns a single column
         condition = expr._call(self)[0]
         spark_df = self._native_frame.where(condition)
         return self._from_native_frame(spark_df)

tests/dtypes_test.py

@@ -203,7 +203,7 @@ def test_pandas_fixed_offset_1302() -> None:
 def test_huge_int() -> None:
     df = pl.DataFrame({"a": [1, 2, 3]})
     if POLARS_VERSION >= (1, 18):  # pragma: no cover
-        result = nw.from_native(df).schema
+        result = nw.from_native(df.select(pl.col("a").cast(pl.Int128))).schema
         assert result["a"] == nw.Int128
     else:  # pragma: no cover
         # Int128 was not available yet
@@ -221,13 +221,6 @@ def test_huge_int() -> None:
     result = nw.from_native(rel).schema
     assert result["a"] == nw.UInt128
 
-    if POLARS_VERSION >= (1, 18):  # pragma: no cover
-        result = nw.from_native(df).schema
-        assert result["a"] == nw.UInt128
-    else:  # pragma: no cover
-        # UInt128 was not available yet
-        pass
-
     # TODO(unassigned): once other libraries support Int128/UInt128,
     # add tests for them too
 

tests/frame/concat_test.py

@@ -44,9 +44,15 @@ def test_concat_vertical(constructor: Constructor) -> None:
     with pytest.raises(ValueError, match="No items"):
         nw.concat([], how="vertical")
 
-    with pytest.raises((Exception, TypeError), match="unable to vstack"):
+    with pytest.raises(
+        (Exception, TypeError),
+        match="unable to vstack|inputs should all have the same schema",
+    ):
         nw.concat([df_left, df_right.rename({"d": "i"})], how="vertical").collect()
-    with pytest.raises((Exception, TypeError), match="unable to vstack|unable to append"):
+    with pytest.raises(
+        (Exception, TypeError),
+        match="unable to vstack|unable to append|inputs should all have the same schema",
+    ):
         nw.concat([df_left, df_left.select("d")], how="vertical").collect()