From 9a298eed4a746a459ba1c6d2b0dfa0ba44b58612 Mon Sep 17 00:00:00 2001
From: Brock <jbrockmendel@gmail.com>
Date: Tue, 4 Jul 2023 12:18:20 -0700
Subject: [PATCH] CLN: is_mixed_type

---
 pandas/core/frame.py                   | 29 ++++----------------------
 pandas/core/generic.py                 | 11 +++++-----
 pandas/core/internals/array_manager.py |  4 ----
 pandas/core/series.py                  |  5 -----
 4 files changed, 9 insertions(+), 40 deletions(-)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index ae43a44d68f1c..f90b5c0eedbe8 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -961,13 +961,6 @@ def _is_homogeneous_type(self) -> bool:
         -------
         bool
 
-        See Also
-        --------
-        Index._is_homogeneous_type : Whether the object has a single
-            dtype.
-        MultiIndex._is_homogeneous_type : Whether all the levels of a
-            MultiIndex have the same dtype.
-
         Examples
         --------
         >>> DataFrame({"A": [1, 2], "B": [3, 4]})._is_homogeneous_type
@@ -983,12 +976,8 @@ def _is_homogeneous_type(self) -> bool:
         ...    "B": np.array([1, 2], dtype=np.int64)})._is_homogeneous_type
         False
         """
-        if isinstance(self._mgr, ArrayManager):
-            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
-        else:
-            return not self._is_mixed_type
+        # The "<" part of "<=" here is for empty DataFrame cases
+        return len({arr.dtype for arr in self._mgr.arrays}) <= 1
 
     @property
     def _can_fast_transpose(self) -> bool:
@@ -4958,7 +4947,7 @@ def _reindex_multi(
         if row_indexer is not None and col_indexer is not None:
             # Fastpath. By doing two 'take's at once we avoid making an
             #  unnecessary copy.
-            # We only get here with `not self._is_mixed_type`, which (almost)
+            # We only get here with `self._can_fast_transpose`, which (almost)
             #  ensures that self.values is cheap. It may be worth making this
             #  condition more specific.
             indexer = row_indexer, col_indexer
@@ -10849,17 +10838,7 @@ def count(self, axis: Axis = 0, numeric_only: bool = False):
         if len(frame._get_axis(axis)) == 0:
             result = self._constructor_sliced(0, index=frame._get_agg_axis(axis))
         else:
-            if frame._is_mixed_type or frame._mgr.any_extension_types:
-                # the or any_extension_types is really only hit for single-
-                # column frames with an extension array
-                result = notna(frame).sum(axis=axis)
-            else:
-                # GH13407
-                series_counts = notna(frame).sum(axis=axis)
-                counts = series_counts._values
-                result = self._constructor_sliced(
-                    counts, index=frame._get_agg_axis(axis), copy=False
-                )
+            result = notna(frame).sum(axis=axis)
 
         return result.astype("int64").__finalize__(self, method="count")
 
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index f049e9d479b26..ec0f477a7d0ff 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -5536,12 +5536,9 @@ def _needs_reindex_multi(self, axes, method, level: Level | None) -> bool_t:
             (common.count_not_none(*axes.values()) == self._AXIS_LEN)
             and method is None
             and level is None
-            and not self._is_mixed_type
-            and not (
-                self.ndim == 2
-                and len(self.dtypes) == 1
-                and isinstance(self.dtypes.iloc[0], ExtensionDtype)
-            )
+            # reindex_multi calls self.values, so we only want to go
+            #  down that path when doing so is cheap.
+            and self._can_fast_transpose
         )
 
     def _reindex_multi(self, axes, copy, fill_value):
@@ -6266,9 +6263,11 @@ def _consolidate(self):
             self
         )
 
+    @final
     @property
     def _is_mixed_type(self) -> bool_t:
         if self._mgr.is_single_block:
+            # Includes all Series cases
             return False
 
         if self._mgr.any_extension_types:
diff --git a/pandas/core/internals/array_manager.py b/pandas/core/internals/array_manager.py
index f402c9ced0e19..431de70a25392 100644
--- a/pandas/core/internals/array_manager.py
+++ b/pandas/core/internals/array_manager.py
@@ -347,10 +347,6 @@ def _convert(arr):
     def to_native_types(self, **kwargs) -> Self:
         return self.apply(to_native_types, **kwargs)
 
-    @property
-    def is_mixed_type(self) -> bool:
-        return True
-
     @property
     def any_extension_types(self) -> bool:
         """Whether any of the blocks in this manager are extension blocks"""
diff --git a/pandas/core/series.py b/pandas/core/series.py
index e59a4cfc3fcc1..e1b76fe132a11 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -1383,7 +1383,6 @@ def _maybe_update_cacher(
             return
         cacher = getattr(self, "_cacher", None)
         if cacher is not None:
-            assert self.ndim == 1
             ref: DataFrame = cacher[1]()
 
             # we are trying to reference a dead referent, hence
@@ -1407,10 +1406,6 @@ def _maybe_update_cacher(
     # ----------------------------------------------------------------------
     # Unsorted
 
-    @property
-    def _is_mixed_type(self) -> bool:
-        return False
-
     def repeat(self, repeats: int | Sequence[int], axis: None = None) -> Series:
         """
         Repeat elements of a Series.