exclude "expanding empty df" case

pandas-dev · Nov 28, 2023 · b1a4777 · b1a4777
1 parent 27bf409
commit b1a4777
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Showing 2 changed files with 7 additions and 7 deletions.
diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
@@ -2112,9 +2112,7 @@ def _setitem_single_column(self, loc: int, value, plane_indexer) -> None:
                 #  then we can use value's dtype (or inferred dtype)
                 #  instead of object
                 dtype = self.obj.dtypes.iloc[loc]
-                if dtype not in (np.void, object) and not isinstance(
-                    value, ABCDataFrame
-                ):
+                if dtype != np.void and not (self.obj.empty):
                     # Exclude np.void, as that is a special case for expansion.
                     #   We want to warn for
                     #       df = pd.DataFrame({'a': [1, 2], 'b': [3, 4]})
@@ -2123,7 +2121,6 @@ def _setitem_single_column(self, loc: int, value, plane_indexer) -> None:
                     #       df = pd.DataFrame({'a': [1, 2], 'b': [3, 4]})
                     #       df.loc[:, 'b'] = .3
                     # Exclude `object`, as then no upcasting happens.
-                    # Exclude ABCDataFrame due to https://github.com/pandas-dev/pandas/issues/56223
                     warnings.warn(
                         f"Setting an item of incompatible dtype is deprecated "
                         "and will raise in a future error of pandas. "

diff --git a/pandas/tests/indexing/test_loc.py b/pandas/tests/indexing/test_loc.py
@@ -1207,8 +1207,7 @@ def test_loc_setitem_empty_append_expands_rows_mixed_dtype(self):
 
         df = DataFrame(columns=["x", "y"])
         df["x"] = df["x"].astype(np.int64)
-        with tm.assert_produces_warning(FutureWarning, match="incompatible dtype"):
-            df.loc[:, "x"] = data
+        df.loc[:, "x"] = data
         tm.assert_frame_equal(df, expected)
 
     def test_loc_setitem_empty_append_single_value(self):
@@ -1488,7 +1487,11 @@ def test_loc_setitem_datetimeindex_tz(self, idxer, tz_naive_fixture):
         # if result started off with object dtype, then the .loc.__setitem__
         #  below would retain object dtype
         result = DataFrame(index=idx, columns=["var"], dtype=np.float64)
-        result.loc[:, idxer] = expected
+        with tm.assert_produces_warning(
+            FutureWarning if idxer == "var" else None, match="incompatible dtype"
+        ):
+            # See https://github.com/pandas-dev/pandas/issues/56223
+            result.loc[:, idxer] = expected
         tm.assert_frame_equal(result, expected)
 
     def test_loc_setitem_time_key(self, using_array_manager):