CLN: remove Block.array_dtype, SingleBlockManager.array_dtype (pandas-dev#32612)

Author: jbrockmendel

pandas/core/internals/blocks.py

@@ -11,7 +11,6 @@
 import pandas._libs.internals as libinternals
 from pandas._libs.tslibs import Timedelta, conversion
 from pandas._libs.tslibs.timezones import tz_compare
-from pandas._typing import DtypeObj
 from pandas.util._validators import validate_bool_kwarg
 
 from pandas.core.dtypes.cast import (
@@ -256,14 +255,6 @@ def mgr_locs(self, new_mgr_locs):
 
         self._mgr_locs = new_mgr_locs
 
-    @property
-    def array_dtype(self) -> DtypeObj:
-        """
-        the dtype to return if I want to construct this block as an
-        array
-        """
-        return self.dtype
-
     def make_block(self, values, placement=None) -> "Block":
         """
         Create a new block, with type inference propagate any values that are
@@ -2921,14 +2912,6 @@ def __init__(self, values, placement, ndim=None):
     def _holder(self):
         return Categorical
 
-    @property
-    def array_dtype(self):
-        """
-        the dtype to return if I want to construct this block as an
-        array
-        """
-        return np.object_
-
     def to_dense(self):
         # Categorical.get_values returns a DatetimeIndex for datetime
         # categories, so we can't simply use `np.asarray(self.values)` like

pandas/core/internals/managers.py

@@ -193,8 +193,10 @@ def make_empty(self: T, axes=None) -> T:
         # preserve dtype if possible
         if self.ndim == 1:
             assert isinstance(self, SingleBlockManager)  # for mypy
-            arr = np.array([], dtype=self.array_dtype)
-            blocks = [make_block(arr, placement=slice(0, 0), ndim=1)]
+            blk = self.blocks[0]
+            arr = blk.values[:0]
+            nb = blk.make_block_same_class(arr, placement=slice(0, 0), ndim=1)
+            blocks = [nb]
         else:
             blocks = []
         return type(self).from_blocks(blocks, axes)
@@ -1585,10 +1587,6 @@ def index(self) -> Index:
     def dtype(self) -> DtypeObj:
         return self._block.dtype
 
-    @property
-    def array_dtype(self) -> DtypeObj:
-        return self._block.array_dtype
-
     def get_dtype_counts(self):
         return {self.dtype.name: 1}