Backport PR #38679: Revert "Deprecated casting an object-dtype index …

…of datetime objects to DatetimeIndex in the Series constructor (23598)" (#38699)

Co-authored-by: Simon Hawkins <simonjayhawkins@gmail.com>

doc/source/whatsnew/v1.2.0.rst

@@ -524,7 +524,6 @@ Deprecations
 - Deprecated indexing :class:`DataFrame` rows with a single datetime-like string as ``df[string]``
   (given the ambiguity whether it is indexing the rows or selecting a column), use
   ``df.loc[string]`` instead (:issue:`36179`)
-- Deprecated casting an object-dtype index of ``datetime`` objects to :class:`.DatetimeIndex` in the :class:`Series` constructor (:issue:`23598`)
 - Deprecated :meth:`Index.is_all_dates` (:issue:`27744`)
 - The default value of ``regex`` for :meth:`Series.str.replace` will change from ``True`` to ``False`` in a future release. In addition, single character regular expressions will *not* be treated as literal strings when ``regex=True`` is set. (:issue:`24804`)
 - Deprecated automatic alignment on comparison operations between :class:`DataFrame` and :class:`Series`, do ``frame, ser = frame.align(ser, axis=1, copy=False)`` before e.g. ``frame == ser`` (:issue:`28759`)

pandas/core/generic.py

@@ -9689,12 +9689,6 @@ def truncate(
         # if we have a date index, convert to dates, otherwise
         # treat like a slice
         if ax._is_all_dates:
-            if is_object_dtype(ax.dtype):
-                warnings.warn(
-                    "Treating object-dtype Index of date objects as DatetimeIndex "
-                    "is deprecated, will be removed in a future version.",
-                    FutureWarning,
-                )
             from pandas.core.tools.datetimes import to_datetime
 
             before = to_datetime(before)

pandas/core/series.py

@@ -430,13 +430,6 @@ def _set_axis(self, axis: int, labels, fastpath: bool = False) -> None:
                     # need to set here because we changed the index
                     if fastpath:
                         self._mgr.set_axis(axis, labels)
-                    warnings.warn(
-                        "Automatically casting object-dtype Index of datetimes to "
-                        "DatetimeIndex is deprecated and will be removed in a "
-                        "future version.  Explicitly cast to DatetimeIndex instead.",
-                        FutureWarning,
-                        stacklevel=3,
-                    )
                 except (tslibs.OutOfBoundsDatetime, ValueError):
                     # labels may exceeds datetime bounds,
                     # or not be a DatetimeIndex

pandas/tests/indexing/test_indexing.py

@@ -535,9 +535,7 @@ def test_string_slice(self):
             df["2011"]
 
         with pytest.raises(KeyError, match="'2011'"):
-            with tm.assert_produces_warning(FutureWarning):
-                # This does an is_all_dates check
-                df.loc["2011", 0]
+            df.loc["2011", 0]
 
         df = DataFrame()
         assert not df.index._is_all_dates

pandas/tests/io/pytables/test_store.py

@@ -2358,17 +2358,13 @@ def test_series(self, setup_path):
         ts = tm.makeTimeSeries()
         self._check_roundtrip(ts, tm.assert_series_equal, path=setup_path)
 
-        with tm.assert_produces_warning(FutureWarning):
-            # auto-casting object->DatetimeIndex deprecated
-            ts2 = Series(ts.index, Index(ts.index, dtype=object))
+        ts2 = Series(ts.index, Index(ts.index, dtype=object))
         self._check_roundtrip(ts2, tm.assert_series_equal, path=setup_path)
 
-        with tm.assert_produces_warning(FutureWarning):
-            # auto-casting object->DatetimeIndex deprecated
-            ts3 = Series(
-                ts.values, Index(np.asarray(ts.index, dtype=object), dtype=object)
-            )
-        self._check_roundtrip(ts3, tm.assert_series_equal, path=setup_path)
+        ts3 = Series(ts.values, Index(np.asarray(ts.index, dtype=object), dtype=object))
+        self._check_roundtrip(
+            ts3, tm.assert_series_equal, path=setup_path, check_index_type=False
+        )
 
     def test_float_index(self, setup_path):
 

pandas/tests/plotting/test_datetimelike.py

@@ -277,16 +277,9 @@ def test_irreg_hf(self):
         _, ax = self.plt.subplots()
         df2 = df.copy()
         df2.index = df.index.astype(object)
-        with tm.assert_produces_warning(FutureWarning, check_stacklevel=False):
-            # This warning will be emitted
-            # pandas/core/frame.py:3216:
-            # FutureWarning: Automatically casting object-dtype Index of datetimes
-            # to DatetimeIndex is deprecated and will be removed in a future version.
-            # Explicitly cast to DatetimeIndex instead.
-            # return klass(values, index=self.index, name=name, fastpath=True)
-            df2.plot(ax=ax)
-            diffs = Series(ax.get_lines()[0].get_xydata()[:, 0]).diff()
-            assert (np.fabs(diffs[1:] - sec) < 1e-8).all()
+        df2.plot(ax=ax)
+        diffs = Series(ax.get_lines()[0].get_xydata()[:, 0]).diff()
+        assert (np.fabs(diffs[1:] - sec) < 1e-8).all()
 
     def test_irregular_datetime64_repr_bug(self):
         ser = tm.makeTimeSeries()
@@ -997,16 +990,9 @@ def test_irreg_dtypes(self):
         # np.datetime64
         idx = date_range("1/1/2000", periods=10)
         idx = idx[[0, 2, 5, 9]].astype(object)
-        with tm.assert_produces_warning(FutureWarning, check_stacklevel=False):
-            # This warning will be emitted
-            # pandas/core/frame.py:3216:
-            # FutureWarning: Automatically casting object-dtype Index of datetimes
-            # to DatetimeIndex is deprecated and will be removed in a future version.
-            # Explicitly cast to DatetimeIndex instead.
-            # return klass(values, index=self.index, name=name, fastpath=True)
-            df = DataFrame(np.random.randn(len(idx), 3), idx)
-            _, ax = self.plt.subplots()
-            _check_plot_works(df.plot, ax=ax)
+        df = DataFrame(np.random.randn(len(idx), 3), idx)
+        _, ax = self.plt.subplots()
+        _check_plot_works(df.plot, ax=ax)
 
     def test_time(self):
         t = datetime(1, 1, 1, 3, 30, 0)

pandas/tests/series/test_constructors.py

@@ -1614,8 +1614,7 @@ def test_constructor_infer_index_tz(self):
 class TestSeriesConstructorIndexCoercion:
     def test_series_constructor_datetimelike_index_coercion(self):
         idx = tm.makeDateIndex(10000)
-        with tm.assert_produces_warning(FutureWarning):
-            ser = Series(np.random.randn(len(idx)), idx.astype(object))
+        ser = Series(np.random.randn(len(idx)), idx.astype(object))
         with tm.assert_produces_warning(FutureWarning):
             assert ser.index.is_all_dates
         assert isinstance(ser.index, DatetimeIndex)

pandas/tests/series/test_repr.py

@@ -184,9 +184,7 @@ def test_timeseries_repr_object_dtype(self):
         index = Index(
             [datetime(2000, 1, 1) + timedelta(i) for i in range(1000)], dtype=object
         )
-        with tm.assert_produces_warning(FutureWarning):
-            # Index.is_all_dates deprecated
-            ts = Series(np.random.randn(len(index)), index)
+        ts = Series(np.random.randn(len(index)), index)
         repr(ts)
 
         ts = tm.makeTimeSeries(1000)

pandas/tests/window/moments/test_moments_rolling_apply.py

@@ -122,16 +122,13 @@ def test_center_reindex_series(raw, series):
     s = [f"x{x:d}" for x in range(12)]
     minp = 10
 
-    warn = None if raw else FutureWarning
-    with tm.assert_produces_warning(warn, check_stacklevel=False):
-        # GH#36697 is_all_dates deprecated
-        series_xp = (
-            series.reindex(list(series.index) + s)
-            .rolling(window=25, min_periods=minp)
-            .apply(f, raw=raw)
-            .shift(-12)
-            .reindex(series.index)
-        )
+    series_xp = (
+        series.reindex(list(series.index) + s)
+        .rolling(window=25, min_periods=minp)
+        .apply(f, raw=raw)
+        .shift(-12)
+        .reindex(series.index)
+    )
     series_rs = series.rolling(window=25, min_periods=minp, center=True).apply(
         f, raw=raw
     )
@@ -143,15 +140,12 @@ def test_center_reindex_frame(raw, frame):
     s = [f"x{x:d}" for x in range(12)]
     minp = 10
 
-    warn = None if raw else FutureWarning
-    with tm.assert_produces_warning(warn, check_stacklevel=False):
-        # GH#36697 is_all_dates deprecated
-        frame_xp = (
-            frame.reindex(list(frame.index) + s)
-            .rolling(window=25, min_periods=minp)
-            .apply(f, raw=raw)
-            .shift(-12)
-            .reindex(frame.index)
-        )
+    frame_xp = (
+        frame.reindex(list(frame.index) + s)
+        .rolling(window=25, min_periods=minp)
+        .apply(f, raw=raw)
+        .shift(-12)
+        .reindex(frame.index)
+    )
     frame_rs = frame.rolling(window=25, min_periods=minp, center=True).apply(f, raw=raw)
     tm.assert_frame_equal(frame_xp, frame_rs)