add inplace keyword

Author: jorisvandenbossche

pandas/core/frame.py

@@ -3932,8 +3932,9 @@ def _set_value(
             # error: Argument 2 to "column_setitem" of "BlockManager" has
             # incompatible type "Union[Hashable, Sequence[Hashable]]";
             # expected "Union[int, slice, ndarray[Any, Any]]"
-            self._mgr.column_setitem(icol, iindex, value)  # type: ignore[arg-type]
-            self._clear_item_cache()
+            self._mgr.column_setitem(  # type: ignore[arg-type]
+                icol, iindex, value, inplace=True
+            )
 
         except (KeyError, TypeError, ValueError, LossySetitemError):
             # set using a non-recursive method & reset the cache

pandas/core/internals/array_manager.py

@@ -869,7 +869,9 @@ def iset(
             self.arrays[mgr_idx] = value_arr
         return
 
-    def column_setitem(self, loc: int, idx: int | slice | np.ndarray, value) -> None:
+    def column_setitem(
+        self, loc: int, idx: int | slice | np.ndarray, value, inplace: bool = False
+    ) -> None:
         """
         Set values ("setitem") into a single column (not setting the full column).
 
@@ -879,9 +881,12 @@ def column_setitem(self, loc: int, idx: int | slice | np.ndarray, value) -> None
         arr = self.arrays[loc]
         # create temporary SingleArrayManager without ref to use setitem implementation
         mgr = SingleArrayManager([arr], [self._axes[0]])
-        new_mgr = mgr.setitem((idx,), value)
-        # update existing ArrayManager in-place
-        self.arrays[loc] = new_mgr.arrays[0]
+        if inplace:
+            mgr.setitem_inplace(idx, value)
+        else:
+            new_mgr = mgr.setitem((idx,), value)
+            # update existing ArrayManager in-place
+            self.arrays[loc] = new_mgr.arrays[0]
 
     def insert(self, loc: int, item: Hashable, value: ArrayLike) -> None:
         """

pandas/core/internals/managers.py

@@ -1188,16 +1188,21 @@ def _iset_single(
         self.blocks = new_blocks
         return
 
-    def column_setitem(self, loc: int, idx: int | slice | np.ndarray, value) -> None:
+    def column_setitem(
+        self, loc: int, idx: int | slice | np.ndarray, value, inplace: bool = False
+    ) -> None:
         """
         Set values ("setitem") into a single column (not setting the full column).
 
         This is a method on the BlockManager level, to avoid creating an
         intermediate Series at the DataFrame level (`s = df[loc]; s[idx] = value`)
         """
         col_mgr = self.iget(loc)
-        new_mgr = col_mgr.setitem((idx,), value)
-        self.iset(loc, new_mgr._block.values, inplace=True)
+        if inplace:
+            col_mgr.setitem_inplace(idx, value)
+        else:
+            new_mgr = col_mgr.setitem((idx,), value)
+            self.iset(loc, new_mgr._block.values, inplace=True)
 
     def insert(self, loc: int, item: Hashable, value: ArrayLike) -> None:
         """