feat: add 'weekday' property to DatatimeMethod (#2304)

sycai · web-flow · commit fafd7c732d43 · 2025-12-03T13:36:20.000-06:00
Fixes b/464971054 &#129429;
diff --git a/bigframes/operations/datetimes.py b/bigframes/operations/datetimes.py
@@ -54,6 +54,10 @@ def dayofweek(self) -> series.Series:
     def day_of_week(self) -> series.Series:
         return self.dayofweek
 
+    @property
+    def weekday(self) -> series.Series:
+        return self.dayofweek
+
     @property
     def dayofyear(self) -> series.Series:
         return self._data._apply_unary_op(ops.dayofyear_op)
diff --git a/tests/system/small/operations/test_datetimes.py b/tests/system/small/operations/test_datetimes.py
@@ -108,6 +108,21 @@ def test_dt_day_of_week(scalars_dfs, col_name):
     assert_series_equal(pd_result, bf_result, check_dtype=False)
 
 
+@pytest.mark.parametrize(
+    ("col_name",),
+    DATE_COLUMNS,
+)
+def test_dt_weekday(scalars_dfs, col_name):
+    pytest.importorskip("pandas", minversion="2.0.0")
+    scalars_df, scalars_pandas_df = scalars_dfs
+    bf_series: bigframes.series.Series = scalars_df[col_name]
+
+    bf_result = bf_series.dt.weekday.to_pandas()
+    pd_result = scalars_pandas_df[col_name].dt.weekday
+
+    assert_series_equal(pd_result, bf_result, check_dtype=False)
+
+
 @pytest.mark.parametrize(
     ("col_name",),
     DATE_COLUMNS,
diff --git a/third_party/bigframes_vendored/pandas/core/indexes/accessor.py b/third_party/bigframes_vendored/pandas/core/indexes/accessor.py
@@ -91,6 +91,37 @@ def day_of_week(self):
 
         raise NotImplementedError(constants.ABSTRACT_METHOD_ERROR_MESSAGE)
 
+    @property
+    def weekday(self):
+        """The day of the week with Monday=0, Sunday=6.
+
+        Return the day of the week. It is assumed the week starts on
+        Monday, which is denoted by 0 and ends on Sunday, which is denoted
+        by 6.
+
+        **Examples:**
+
+            >>> s = bpd.Series(
+            ...     pd.date_range('2016-12-31', '2017-01-08', freq='D').to_series()
+            ... )
+            >>> s.dt.weekday
+            2016-12-31 00:00:00    5
+            2017-01-01 00:00:00    6
+            2017-01-02 00:00:00    0
+            2017-01-03 00:00:00    1
+            2017-01-04 00:00:00    2
+            2017-01-05 00:00:00    3
+            2017-01-06 00:00:00    4
+            2017-01-07 00:00:00    5
+            2017-01-08 00:00:00    6
+            dtype: Int64
+
+        Returns:
+            Series: Containing integers indicating the day number.
+        """
+
+        raise NotImplementedError(constants.ABSTRACT_METHOD_ERROR_MESSAGE)
+
     @property
     def day_name(self):
         """
