DEPR: Series.ravel

Author: Tristan Marechaux

doc/source/whatsnew/v2.1.0.rst

@@ -235,6 +235,7 @@ Deprecations
 - Deprecated :func:`is_interval_dtype`, check ``isinstance(dtype, pd.IntervalDtype)`` instead (:issue:`52607`)
 - Deprecated :meth:`DataFrame.applymap`. Use the new :meth:`DataFrame.map` method instead (:issue:`52353`)
 - Deprecated :meth:`DataFrame.swapaxes` and :meth:`Series.swapaxes`, use :meth:`DataFrame.transpose` or :meth:`Series.transpose` instead (:issue:`51946`)
+- Deprecated :meth:`Series.ravel` (:issue:`52511`)
 - Deprecated ``freq`` parameter in :class:`PeriodArray` constructor, pass ``dtype`` instead (:issue:`52462`)
 - Deprecated behavior of :func:`concat` when :class:`DataFrame` has columns that are all-NA, in a future version these will not be discarded when determining the resulting dtype (:issue:`40893`)
 - Deprecated behavior of :meth:`Series.dt.to_pydatetime`, in a future version this will return a :class:`Series` containing python ``datetime`` objects instead of an ``ndarray`` of datetimes; this matches the behavior of other :meth:`Series.dt` properties (:issue:`20306`)
@@ -247,7 +248,6 @@ Deprecations
 - Deprecated the methods :meth:`Series.bool` and :meth:`DataFrame.bool` (:issue:`51749`)
 - Deprecated unused "closed" and "normalize" keywords in the :class:`DatetimeIndex` constructor (:issue:`52628`)
 - Deprecated unused "closed" keyword in the :class:`TimedeltaIndex` constructor (:issue:`52628`)
--
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_210.performance:

pandas/core/dtypes/cast.py

@@ -351,7 +351,7 @@ def trans(x):
             return trans(result).astype(dtype)
 
         # do a test on the first element, if it fails then we are done
-        r = result.ravel()
+        r = np.ravel(result)
         arr = np.array([r[0]])
 
         if isna(arr).any():

pandas/core/series.py

@@ -771,6 +771,13 @@ def ravel(self, order: str = "C") -> ArrayLike:
         --------
         numpy.ndarray.ravel : Return a flattened array.
         """
+        warnings.warn(
+            # GH#52511
+            f"'{type(self).__name__}.ravel' is deprecated and will be removed in a "
+            f"future version.",
+            FutureWarning,
+            stacklevel=find_stack_level(),
+        )
         arr = self._values.ravel(order=order)
         if isinstance(arr, np.ndarray) and using_copy_on_write():
             arr.flags.writeable = False

pandas/tests/series/test_api.py

@@ -142,7 +142,9 @@ def test_ndarray_compat_like_func(self):
     def test_ndarray_compat_ravel(self):
         # ravel
         s = Series(np.random.randn(10))
-        tm.assert_almost_equal(s.ravel(order="F"), s.values.ravel(order="F"))
+        msg = "'Series.ravel' is deprecated"
+        with tm.assert_produces_warning(FutureWarning, match=msg):
+            tm.assert_almost_equal(s.ravel(order="F"), s.values.ravel(order="F"))
 
     def test_empty_method(self):
         s_empty = Series(dtype=object)