fixup for data with no nulls

narwhals-dev · Nov 26, 2024 · 9442ec9 · 9442ec9
1 parent ad20205
commit 9442ec9
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Showing 2 changed files with 24 additions and 39 deletions.
diff --git a/narwhals/_pandas_like/series.py b/narwhals/_pandas_like/series.py
@@ -189,17 +189,18 @@ def ewm_mean(
         ser = self._native_series
         mask_na = ser.isna()
         if self._implementation is Implementation.CUDF:
-            if min_periods == 0 and not ignore_nulls:
+            if (min_periods == 0 and not ignore_nulls) or (not mask_na.any()):
                 result = ser.ewm(com, span, half_life, alpha, adjust).mean()
-            elif min_periods != 0:
-                msg = "`min_periods != 0` is not yet implemented for cuDF"
-                raise NotImplementedError(msg)
             else:
-                msg = "`ignore_nulls=True` is not yet implemented for cuDF"
+                msg = (
+                    "cuDF only supports `ewm_mean` when there are no missing values "
+                    "or when both `min_period=0` and `ignore_nulls=False`"
+                )
                 raise NotImplementedError(msg)
-        result = ser.ewm(
-            com, span, half_life, alpha, min_periods, adjust, ignore_na=ignore_nulls
-        ).mean()
+        else:
+            result = ser.ewm(
+                com, span, half_life, alpha, min_periods, adjust, ignore_na=ignore_nulls
+            ).mean()
         result[mask_na] = None
         return self._from_native_series(result)
 

diff --git a/tests/expr_and_series/ewm_test.py b/tests/expr_and_series/ewm_test.py
@@ -16,9 +16,9 @@
     "ignore:`Expr.ewm_mean` is being called from the stable API although considered an unstable feature."
 )
 def test_ewm_mean_expr(request: pytest.FixtureRequest, constructor: Constructor) -> None:
-    if any(
-        x in str(constructor) for x in ("pyarrow_table_", "dask", "modin", "cudf")
-    ) or ("polars" in str(constructor) and POLARS_VERSION < (1,)):
+    if any(x in str(constructor) for x in ("pyarrow_table_", "dask", "modin")) or (
+        "polars" in str(constructor) and POLARS_VERSION < (1,)
+    ):
         request.applymarker(pytest.mark.xfail)
 
     df = nw.from_native(constructor(data))
@@ -36,7 +36,7 @@ def test_ewm_mean_expr(request: pytest.FixtureRequest, constructor: Constructor)
 def test_ewm_mean_series(
     request: pytest.FixtureRequest, constructor_eager: ConstructorEager
 ) -> None:
-    if any(x in str(constructor_eager) for x in ("pyarrow_table_", "modin", "cudf")) or (
+    if any(x in str(constructor_eager) for x in ("pyarrow_table_", "modin")) or (
         "polars" in str(constructor_eager) and POLARS_VERSION < (1,)
     ):
         request.applymarker(pytest.mark.xfail)
@@ -75,9 +75,9 @@ def test_ewm_mean_expr_adjust(
     adjust: bool,  # noqa: FBT001
     expected: dict[str, list[float]],
 ) -> None:
-    if any(
-        x in str(constructor) for x in ("pyarrow_table_", "dask", "modin", "cudf")
-    ) or ("polars" in str(constructor) and POLARS_VERSION < (1,)):
+    if any(x in str(constructor) for x in ("pyarrow_table_", "dask", "modin")) or (
+        "polars" in str(constructor) and POLARS_VERSION < (1,)
+    ):
         request.applymarker(pytest.mark.xfail)
 
     df = nw.from_native(constructor(data))
@@ -189,40 +189,24 @@ def test_ewm_mean_params(
         df.select(nw.col("a").ewm_mean(span=1.5, half_life=0.75, ignore_nulls=False))
 
 
-@pytest.mark.filterwarnings(
-    "ignore:`Expr.ewm_mean` is being called from the stable API although considered an unstable feature."
-)
-def test_ewm_mean_cudf_default_params(
-    constructor: Constructor,
-    request: pytest.FixtureRequest,
-) -> None:
-    if any(
-        x in str(constructor) for x in ("pyarrow_table_", "dask", "modin", "cudf")
-    ) or ("polars" in str(constructor) and POLARS_VERSION < (1,)):
-        request.applymarker(pytest.mark.xfail)
-    df = nw.from_native(constructor(data))
-    expected: dict[str, list[float | None]] = {"a": [1.0, 1.0, 1.5714285714285714]}
-    assert_equal_data(
-        df.select(nw.col("a").ewm_mean(com=1, min_periods=0)),
-        expected,
-    )
-
-
 @pytest.mark.filterwarnings(
     "ignore:`Expr.ewm_mean` is being called from the stable API although considered an unstable feature."
 )
 def test_ewm_mean_cudf_raise() -> None:  # pragma: no cover
     pytest.importorskip("cudf")
     import cudf
 
-    df = nw.from_native(cudf.DataFrame(data))
+    df_with_nulls = nw.from_native(cudf.DataFrame({"a": [2.0, 4.0, None, 3.0]}))
+    df_ignore_nulls = nw.from_native(cudf.DataFrame(data))
     with pytest.raises(
         NotImplementedError,
-        match="`min_periods != 0` is not yet implemented for cuDF",
+        match="cuDF only supports `ewm_mean` when there are no missing values",
     ):
-        df.select(nw.col("a").ewm_mean(com=1))
+        df_with_nulls.select(nw.col("a").ewm_mean(com=1))
     with pytest.raises(
         NotImplementedError,
-        match="`ignore_nulls=True` is not yet implemented for cuDF",
+        match="cuDF only supports `ewm_mean` when there are no missing values",
     ):
-        df.select(nw.col("a").ewm_mean(com=1, min_periods=0, ignore_nulls=True))
+        df_ignore_nulls.select(
+            nw.col("a").ewm_mean(com=1, min_periods=0, ignore_nulls=True)
+        )