PERF: fastpath DataFrame constructor from BlockManager (#33357)

Author: jbrockmendel

pandas/core/apply.py

@@ -166,9 +166,8 @@ def get_result(self):
         elif isinstance(self.f, np.ufunc):
             with np.errstate(all="ignore"):
                 results = self.obj._mgr.apply("apply", func=self.f)
-            return self.obj._constructor(
-                data=results, index=self.index, columns=self.columns, copy=False
-            )
+            # _constructor will retain self.index and self.columns
+            return self.obj._constructor(data=results)
 
         # broadcasting
         if self.result_type == "broadcast":

pandas/core/frame.py

@@ -434,6 +434,11 @@ def __init__(
             data = data._mgr
 
         if isinstance(data, BlockManager):
+            if index is None and columns is None and dtype is None and copy is False:
+                # GH#33357 fastpath
+                NDFrame.__init__(self, data)
+                return
+
             mgr = self._init_mgr(
                 data, axes=dict(index=index, columns=columns), dtype=dtype, copy=copy
             )

pandas/core/generic.py

@@ -213,13 +213,13 @@ def __init__(
         object.__setattr__(self, "_attrs", attrs)
 
     @classmethod
-    def _init_mgr(cls, mgr, axes=None, dtype=None, copy=False):
+    def _init_mgr(cls, mgr, axes, dtype=None, copy: bool = False) -> BlockManager:
         """ passed a manager and a axes dict """
         for a, axe in axes.items():
             if axe is not None:
-                mgr = mgr.reindex_axis(
-                    axe, axis=cls._get_block_manager_axis(a), copy=False
-                )
+                axe = ensure_index(axe)
+                bm_axis = cls._get_block_manager_axis(a)
+                mgr = mgr.reindex_axis(axe, axis=bm_axis, copy=False)
 
         # make a copy if explicitly requested
         if copy:

pandas/core/series.py

@@ -204,6 +204,17 @@ def __init__(
         self, data=None, index=None, dtype=None, name=None, copy=False, fastpath=False
     ):
 
+        if (
+            isinstance(data, SingleBlockManager)
+            and index is None
+            and dtype is None
+            and copy is False
+        ):
+            # GH#33357 called with just the SingleBlockManager
+            NDFrame.__init__(self, data)
+            self.name = name
+            return
+
         # we are called internally, so short-circuit
         if fastpath:
 
@@ -827,9 +838,8 @@ def take(self, indices, axis=0, is_copy=None, **kwargs) -> "Series":
         new_index = self.index.take(indices)
         new_values = self._values.take(indices)
 
-        return self._constructor(
-            new_values, index=new_index, fastpath=True
-        ).__finalize__(self, method="take")
+        result = self._constructor(new_values, index=new_index, fastpath=True)
+        return result.__finalize__(self, method="take")
 
     def _take_with_is_copy(self, indices, axis=0):
         """