BUG: Change FutureWarning to DeprecationWarning for inplace setitem with DataFrame.(i)loc (#50044)

Co-authored-by: Marc Garcia <[email protected]>
Co-authored-by: Matthew Roeschke <[email protected]>

Author: 3 people

doc/source/whatsnew/v1.5.3.rst

@@ -48,6 +48,7 @@ Other
     as pandas works toward compatibility with SQLAlchemy 2.0.
 
 - Reverted deprecation (:issue:`45324`) of behavior of :meth:`Series.__getitem__` and :meth:`Series.__setitem__` slicing with an integer :class:`Index`; this will remain positional (:issue:`49612`)
+- A ``FutureWarning`` raised when attempting to set values inplace with :meth:`DataFrame.loc` or :meth:`DataFrame.loc` has been changed to a ``DeprecationWarning`` (:issue:`48673`)
 -
 
 .. ---------------------------------------------------------------------------

pandas/core/indexing.py

@@ -2026,7 +2026,7 @@ def _setitem_single_column(self, loc: int, value, plane_indexer):
                     "array. To retain the old behavior, use either "
                     "`df[df.columns[i]] = newvals` or, if columns are non-unique, "
                     "`df.isetitem(i, newvals)`",
-                    FutureWarning,
+                    DeprecationWarning,
                     stacklevel=find_stack_level(),
                 )
                 # TODO: how to get future behavior?

pandas/tests/extension/base/setitem.py

@@ -400,7 +400,7 @@ def test_setitem_frame_2d_values(self, data):
         warn = None
         if has_can_hold_element and not isinstance(data.dtype, PandasDtype):
             # PandasDtype excluded because it isn't *really* supported.
-            warn = FutureWarning
+            warn = DeprecationWarning
 
         with tm.assert_produces_warning(warn, match=msg):
             df.iloc[:] = df

pandas/tests/frame/indexing/test_indexing.py

@@ -785,7 +785,7 @@ def test_getitem_setitem_float_labels(self, using_array_manager):
         assert len(result) == 5
 
         cp = df.copy()
-        warn = FutureWarning if using_array_manager else None
+        warn = DeprecationWarning if using_array_manager else None
         msg = "will attempt to set the values inplace"
         with tm.assert_produces_warning(warn, match=msg):
             cp.loc[1.0:5.0] = 0

pandas/tests/frame/indexing/test_setitem.py

@@ -408,7 +408,7 @@ def test_setitem_frame_length_0_str_key(self, indexer):
 
     def test_setitem_frame_duplicate_columns(self, using_array_manager):
         # GH#15695
-        warn = FutureWarning if using_array_manager else None
+        warn = DeprecationWarning if using_array_manager else None
         msg = "will attempt to set the values inplace"
 
         cols = ["A", "B", "C"] * 2

pandas/tests/frame/indexing/test_where.py

@@ -384,7 +384,7 @@ def test_where_datetime(self, using_array_manager):
         expected = df.copy()
         expected.loc[[0, 1], "A"] = np.nan
 
-        warn = FutureWarning if using_array_manager else None
+        warn = DeprecationWarning if using_array_manager else None
         msg = "will attempt to set the values inplace"
         with tm.assert_produces_warning(warn, match=msg):
             expected.loc[:, "C"] = np.nan
@@ -571,7 +571,7 @@ def test_where_axis_multiple_dtypes(self, using_array_manager):
 
         d2 = df.copy().drop(1, axis=1)
         expected = df.copy()
-        warn = FutureWarning if using_array_manager else None
+        warn = DeprecationWarning if using_array_manager else None
         msg = "will attempt to set the values inplace"
         with tm.assert_produces_warning(warn, match=msg):
             expected.loc[:, 1] = np.nan

pandas/tests/frame/methods/test_dropna.py

@@ -221,7 +221,7 @@ def test_dropna_with_duplicate_columns(self):
         df.iloc[0, 0] = np.nan
         df.iloc[1, 1] = np.nan
         msg = "will attempt to set the values inplace instead"
-        with tm.assert_produces_warning(FutureWarning, match=msg):
+        with tm.assert_produces_warning(DeprecationWarning, match=msg):
             df.iloc[:, 3] = np.nan
         expected = df.dropna(subset=["A", "B", "C"], how="all")
         expected.columns = ["A", "A", "B", "C"]

pandas/tests/frame/methods/test_rename.py

@@ -178,7 +178,9 @@ def test_rename_nocopy(self, float_frame, using_copy_on_write):
 
         # TODO(CoW) this also shouldn't warn in case of CoW, but the heuristic
         # checking if the array shares memory doesn't work if CoW happened
-        with tm.assert_produces_warning(FutureWarning if using_copy_on_write else None):
+        with tm.assert_produces_warning(
+            DeprecationWarning if using_copy_on_write else None
+        ):
             # This loc setitem already happens inplace, so no warning
             #  that this will change in the future
             renamed.loc[:, "foo"] = 1.0

pandas/tests/frame/methods/test_shift.py

@@ -372,7 +372,7 @@ def test_shift_duplicate_columns(self, using_array_manager):
 
         warn = None
         if using_array_manager:
-            warn = FutureWarning
+            warn = DeprecationWarning
 
         shifted = []
         for columns in column_lists:

pandas/tests/frame/test_constructors.py

@@ -2604,7 +2604,9 @@ def check_views(c_only: bool = False):
 
         # FIXME(GH#35417): until GH#35417, iloc.setitem into EA values does not preserve
         #  view, so we have to check in the other direction
-        with tm.assert_produces_warning(FutureWarning, match="will attempt to set"):
+        with tm.assert_produces_warning(
+            DeprecationWarning, match="will attempt to set"
+        ):
             df.iloc[:, 2] = pd.array([45, 46], dtype=c.dtype)
         assert df.dtypes.iloc[2] == c.dtype
         if not copy and not using_copy_on_write: