order matters?

narwhals-dev · Sep 12, 2024 · 4896df2 · 4896df2
1 parent 121f6f8
commit 4896df2
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Showing 2 changed files with 12 additions and 11 deletions.
diff --git a/narwhals/_polars/utils.py b/narwhals/_polars/utils.py
@@ -61,14 +61,14 @@ def translate_dtype(dtype: Any) -> dtypes.DType:
         return dtypes.Categorical()
     if dtype == pl.Enum:
         return dtypes.Enum()
-    if isinstance_or_issubclass(dtype, pl.Datetime):
-        time_unit: Literal["us", "ns", "ms"] = getattr(dtype, "time_unit", "us")
-        time_zone = getattr(dtype, "time_zone", None)
-        return dtypes.Datetime(time_unit=time_unit, time_zone=time_zone)
     if dtype == pl.Duration:
         return dtypes.Duration()
     if dtype == pl.Date:
         return dtypes.Date()
+    if isinstance_or_issubclass(dtype, pl.Datetime):
+        time_unit: Literal["us", "ns", "ms"] = getattr(dtype, "time_unit", "us")
+        time_zone = getattr(dtype, "time_zone", None)
+        return dtypes.Datetime(time_unit=time_unit, time_zone=time_zone)
     return dtypes.Unknown()
 
 
@@ -107,12 +107,13 @@ def narwhals_to_native_dtype(dtype: dtypes.DType | type[dtypes.DType]) -> Any:
     if dtype == dtypes.Enum:
         msg = "Converting to Enum is not (yet) supported"
         raise NotImplementedError(msg)
-    if isinstance_or_issubclass(dtype, dtypes.Datetime):
-        time_unit = getattr(dtype, "time_unit", "us")
-        time_zone = getattr(dtype, "time_zone", None)
-        return pl.Datetime(time_unit, time_zone)
     if dtype == dtypes.Duration:
         return pl.Duration()
     if dtype == dtypes.Date:
         return pl.Date()
+    if isinstance_or_issubclass(dtype, dtypes.Datetime):
+        time_unit = getattr(dtype, "time_unit", "us")
+        time_zone = getattr(dtype, "time_zone", None)
+        return pl.Datetime(time_unit, time_zone)
+
     return pl.Unknown()  # pragma: no cover
diff --git a/tests/series_only/cast_test.py b/tests/series_only/cast_test.py
@@ -75,13 +75,13 @@ def test_cast_date_datetime_pandas() -> None:
     df = df.select(nw.col("a").cast(nw.Datetime))
     result = nw.to_native(df)
     expected = pd.DataFrame({"a": [datetime(2020, 1, 1), datetime(2020, 1, 2)]}).astype(
-        {"a": "timestamp[ns][pyarrow]"}
+        {"a": "timestamp[us][pyarrow]"}
     )
     pd.testing.assert_frame_equal(result, expected)
 
-    # pandas: pyarrow datetime to date
+    # # pandas: pyarrow datetime to date
     dfpd = pd.DataFrame({"a": [datetime(2020, 1, 1), datetime(2020, 1, 2)]}).astype(
-        {"a": "timestamp[ns][pyarrow]"}
+        {"a": "timestamp[us][pyarrow]"}
     )
     df = nw.from_native(dfpd)
     df = df.select(nw.col("a").cast(nw.Date))