CLN: remove unused legacy pickle compat code (#31078)

Author: jbrockmendel

pandas/core/generic.py

@@ -1928,9 +1928,9 @@ def __setstate__(self, state):
                         object.__setattr__(self, k, v)
 
             else:
-                self._unpickle_series_compat(state)
+                raise NotImplementedError("Pre-0.12 pickles are no longer supported")
         elif len(state) == 2:
-            self._unpickle_series_compat(state)
+            raise NotImplementedError("Pre-0.12 pickles are no longer supported")
 
         self._item_cache = {}
 

pandas/core/internals/managers.py

@@ -279,30 +279,7 @@ def unpickle_block(values, mgr_locs):
                 unpickle_block(b["values"], b["mgr_locs"]) for b in state["blocks"]
             )
         else:
-            # discard anything after 3rd, support beta pickling format for a
-            # little while longer
-            ax_arrays, bvalues, bitems = state[:3]
-
-            self.axes = [ensure_index(ax) for ax in ax_arrays]
-
-            if len(bitems) == 1 and self.axes[0].equals(bitems[0]):
-                # This is a workaround for pre-0.14.1 pickles that didn't
-                # support unpickling multi-block frames/panels with non-unique
-                # columns/items, because given a manager with items ["a", "b",
-                # "a"] there's no way of knowing which block's "a" is where.
-                #
-                # Single-block case can be supported under the assumption that
-                # block items corresponded to manager items 1-to-1.
-                all_mgr_locs = [slice(0, len(bitems[0]))]
-            else:
-                all_mgr_locs = [
-                    self.axes[0].get_indexer(blk_items) for blk_items in bitems
-                ]
-
-            self.blocks = tuple(
-                unpickle_block(values, mgr_locs)
-                for values, mgr_locs in zip(bvalues, all_mgr_locs)
-            )
+            raise NotImplementedError("pre-0.14.1 pickles are no longer supported")
 
         self._post_setstate()
 

pandas/core/series.py

@@ -744,35 +744,6 @@ def __array__(self, dtype=None) -> np.ndarray:
 
     # ----------------------------------------------------------------------
 
-    def _unpickle_series_compat(self, state) -> None:
-        if isinstance(state, dict):
-            self._data = state["_data"]
-            self.name = state["name"]
-            self.index = self._data.index
-
-        elif isinstance(state, tuple):
-
-            # < 0.12 series pickle
-
-            nd_state, own_state = state
-
-            # recreate the ndarray
-            data = np.empty(nd_state[1], dtype=nd_state[2])
-            np.ndarray.__setstate__(data, nd_state)
-
-            # backwards compat
-            index, name = own_state[0], None
-            if len(own_state) > 1:
-                name = own_state[1]
-
-            # recreate
-            self._data = SingleBlockManager(data, index, fastpath=True)
-            self._index = index
-            self.name = name
-
-        else:
-            raise Exception(f"cannot unpickle legacy formats -> [{state}]")
-
     # indexers
     @property
     def axes(self) -> List[Index]: