BUG: Fixed strange behaviour of pd.DataFrame.drop() with inplace argument (pandas-dev#30484)

Author: rjfs

pandas/core/ops/methods.py

@@ -83,48 +83,6 @@ def add_special_arithmetic_methods(cls):
     new_methods = _create_methods(
         cls, arith_method, comp_method, bool_method, special=True
     )
-    # inplace operators (I feel like these should get passed an `inplace=True`
-    # or just be removed
-
-    def _wrap_inplace_method(method):
-        """
-        return an inplace wrapper for this method
-        """
-
-        def f(self, other):
-            result = method(self, other)
-
-            # this makes sure that we are aligned like the input
-            # we are updating inplace so we want to ignore is_copy
-            self._update_inplace(
-                result.reindex_like(self, copy=False)._data, verify_is_copy=False
-            )
-
-            return self
-
-        f.__name__ = "__i{name}__".format(name=method.__name__.strip("__"))
-        return f
-
-    new_methods.update(
-        dict(
-            __iadd__=_wrap_inplace_method(new_methods["__add__"]),
-            __isub__=_wrap_inplace_method(new_methods["__sub__"]),
-            __imul__=_wrap_inplace_method(new_methods["__mul__"]),
-            __itruediv__=_wrap_inplace_method(new_methods["__truediv__"]),
-            __ifloordiv__=_wrap_inplace_method(new_methods["__floordiv__"]),
-            __imod__=_wrap_inplace_method(new_methods["__mod__"]),
-            __ipow__=_wrap_inplace_method(new_methods["__pow__"]),
-        )
-    )
-
-    new_methods.update(
-        dict(
-            __iand__=_wrap_inplace_method(new_methods["__and__"]),
-            __ior__=_wrap_inplace_method(new_methods["__or__"]),
-            __ixor__=_wrap_inplace_method(new_methods["__xor__"]),
-        )
-    )
-
     _add_methods(cls, new_methods=new_methods)
 
 

pandas/tests/base/test_ops.py

@@ -767,6 +767,27 @@ def test_drop_duplicates_series_vs_dataframe(self):
                 dropped_series = df[column].drop_duplicates(keep=keep)
                 tm.assert_frame_equal(dropped_frame, dropped_series.to_frame())
 
+    def test_inplace_drop_and_add(self):
+        # GH 30484
+        # Get expected df
+        expected = pd.DataFrame({})
+        expected["x1"] = [1, 2, 3, 4, 5]
+        expected["x2"] = [0, 0, 0, 1, 1]
+        expected["target"] = [10, 20, 30, 40, 50]
+        y = expected["target"]
+        expected.drop("target", axis=1, inplace=True)
+        y = y + np.min(y)
+        # Get tested df
+        df = pd.DataFrame({})
+        df["x1"] = [1, 2, 3, 4, 5]
+        df["x2"] = [0, 0, 0, 1, 1]
+        df["target"] = [10, 20, 30, 40, 50]
+        y = df["target"]
+        df.drop("target", axis=1, inplace=True)
+        y += np.min(y)
+        # compare
+        tm.assert_frame_equal(df, expected)
+
     def test_fillna(self):
         # # GH 11343
         # though Index.fillna and Series.fillna has separate impl,