feedback: move change core/generic -> internals

Author: arw2019

pandas/core/generic.py

@@ -66,7 +66,6 @@
     ensure_str,
     is_bool,
     is_bool_dtype,
-    is_categorical_dtype,
     is_datetime64_any_dtype,
     is_datetime64tz_dtype,
     is_dict_like,
@@ -5795,12 +5794,6 @@ def astype(
                 for i in range(len(self.columns))
             ]
 
-        elif is_categorical_dtype(self):
-            new_data = pd.Categorical.from_codes(
-                self.cat.codes, categories=self.cat.categories.astype(dtype)
-            )
-            return self._constructor(new_data).__finalize__(self, method="astype")
-
         else:
             # else, only a single dtype is given
             new_data = self._mgr.astype(dtype=dtype, copy=copy, errors=errors)

pandas/core/internals/blocks.py

@@ -592,7 +592,12 @@ def astype(self, dtype, copy: bool = False, errors: str = "raise"):
 
             if is_categorical_dtype(self.values.dtype):
                 # GH 10696/18593: update an existing categorical efficiently
-                return self.make_block(self.values.astype(dtype, copy=copy))
+                return self.make_block(
+                    Categorical.from_codes(
+                        self.cat.codes, categories=self.cat.categories.astype(dtype)
+                    ),
+                    copy=copy,
+                )
 
             return self.make_block(Categorical(self.values, dtype=dtype))