CLN: helper attribute to check for ArrayManager

pandas/core/frame.py

@@ -866,7 +866,7 @@ def _is_homogeneous_type(self) -> bool:
         ...    "B": np.array([1, 2], dtype=np.int64)})._is_homogeneous_type
         False
         """
-        if isinstance(self._mgr, ArrayManager):
+        if self._using_array_manager:
             return len({arr.dtype for arr in self._mgr.arrays}) == 1
         if self._mgr.any_extension_types:
             return len({block.dtype for block in self._mgr.blocks}) == 1
@@ -878,7 +878,7 @@ def _can_fast_transpose(self) -> bool:
         """
         Can we transpose this DataFrame without creating any new array objects.
         """
-        if isinstance(self._mgr, ArrayManager):
+        if self._using_array_manager:
             return False
         blocks = self._mgr.blocks
         if len(blocks) != 1:

pandas/core/generic.py

@@ -321,6 +321,14 @@ def _as_manager(self: NDFrameT, typ: str, copy: bool_t = True) -> NDFrameT:
         # fastpath of passing a manager doesn't check the option/manager class
         return self._constructor(new_mgr).__finalize__(self)
 
+    @property
+    def _using_array_manager(self) -> bool_t:
+        """
+        Private attribute to quickly check if the DataFrame/Series is
+        backed by an ArrayManager or not.
+        """
+        return isinstance(self._mgr, (ArrayManager, SingleArrayManager))
+
     # ----------------------------------------------------------------------
     # attrs and flags
 
@@ -5606,7 +5614,7 @@ def _protect_consolidate(self, f):
         Consolidate _mgr -- if the blocks have changed, then clear the
         cache
         """
-        if isinstance(self._mgr, (ArrayManager, SingleArrayManager)):
+        if self._using_array_manager:
             return f()
         blocks_before = len(self._mgr.blocks)
         result = f()

pandas/core/indexing.py

@@ -1552,11 +1552,7 @@ def _setitem_with_indexer(self, indexer, value, name="iloc"):
 
         # if there is only one block/type, still have to take split path
         # unless the block is one-dimensional or it can hold the value
-        if (
-            not take_split_path
-            and getattr(self.obj._mgr, "blocks", False)
-            and self.ndim > 1
-        ):
+        if not take_split_path and not self.obj._using_array_manager and self.ndim > 1:
             # in case of dict, keys are indices
             val = list(value.values()) if isinstance(value, dict) else value
             blk = self.obj._mgr.blocks[0]