REF: clearer names in libreduction (pandas-dev#41274)

Author: jbrockmendel

pandas/_libs/reduction.pyx

@@ -63,17 +63,17 @@ cdef class _BaseGrouper:
         )
         return cached_index, cached_series
 
-    cdef inline _update_cached_objs(self, object cached_typ, object cached_ityp,
+    cdef inline _update_cached_objs(self, object cached_series, object cached_index,
                                     Slider islider, Slider vslider):
         # See the comment in indexes/base.py about _index_data.
         # We need this for EA-backed indexes that have a reference
         # to a 1-d ndarray like datetime / timedelta / period.
-        cached_ityp._engine.clear_mapping()
-        cached_ityp._cache.clear()  # e.g. inferred_freq must go
-        cached_typ._mgr.set_values(vslider.buf)
+        cached_index._engine.clear_mapping()
+        cached_index._cache.clear()  # e.g. inferred_freq must go
+        cached_series._mgr.set_values(vslider.buf)
 
     cdef inline object _apply_to_group(self,
-                                       object cached_typ, object cached_ityp,
+                                       object cached_series, object cached_index,
                                        bint initialized):
         """
         Call self.f on our new group, then update to the next group.
@@ -83,7 +83,7 @@ cdef class _BaseGrouper:
 
         # NB: we assume that _update_cached_objs has already cleared cleared
         #  the cache and engine mapping
-        res = self.f(cached_typ)
+        res = self.f(cached_series)
         res = extract_result(res)
         if not initialized:
             # On the first pass, we check the output shape to see
@@ -140,7 +140,7 @@ cdef class SeriesBinGrouper(_BaseGrouper):
             object res
             bint initialized = 0
             Slider vslider, islider
-            object cached_typ = None, cached_ityp = None
+            object cached_series = None, cached_index = None
 
         counts = np.zeros(self.ngroups, dtype=np.int64)
 
@@ -160,7 +160,9 @@ cdef class SeriesBinGrouper(_BaseGrouper):
 
         result = np.empty(self.ngroups, dtype='O')
 
-        cached_ityp, cached_typ = self._init_dummy_series_and_index(islider, vslider)
+        cached_index, cached_series = self._init_dummy_series_and_index(
+            islider, vslider
+        )
 
         start = 0
         try:
@@ -172,9 +174,9 @@ cdef class SeriesBinGrouper(_BaseGrouper):
                 vslider.move(start, end)
 
                 self._update_cached_objs(
-                    cached_typ, cached_ityp, islider, vslider)
+                    cached_series, cached_index, islider, vslider)
 
-                res, initialized = self._apply_to_group(cached_typ, cached_ityp,
+                res, initialized = self._apply_to_group(cached_series, cached_index,
                                                         initialized)
                 start += group_size
 
@@ -236,7 +238,7 @@ cdef class SeriesGrouper(_BaseGrouper):
             object res
             bint initialized = 0
             Slider vslider, islider
-            object cached_typ = None, cached_ityp = None
+            object cached_series = None, cached_index = None
 
         labels = self.labels
         counts = np.zeros(self.ngroups, dtype=np.int64)
@@ -248,7 +250,9 @@ cdef class SeriesGrouper(_BaseGrouper):
 
         result = np.empty(self.ngroups, dtype='O')
 
-        cached_ityp, cached_typ = self._init_dummy_series_and_index(islider, vslider)
+        cached_index, cached_series = self._init_dummy_series_and_index(
+            islider, vslider
+        )
 
         start = 0
         try:
@@ -268,9 +272,9 @@ cdef class SeriesGrouper(_BaseGrouper):
                     vslider.move(start, end)
 
                     self._update_cached_objs(
-                        cached_typ, cached_ityp, islider, vslider)
+                        cached_series, cached_index, islider, vslider)
 
-                    res, initialized = self._apply_to_group(cached_typ, cached_ityp,
+                    res, initialized = self._apply_to_group(cached_series, cached_index,
                                                             initialized)
 
                     start += group_size
@@ -293,20 +297,20 @@ cdef class SeriesGrouper(_BaseGrouper):
         return result, counts
 
 
-cpdef inline extract_result(object res, bint squeeze=True):
+cpdef inline extract_result(object res):
     """ extract the result object, it might be a 0-dim ndarray
         or a len-1 0-dim, or a scalar """
     if hasattr(res, "_values"):
         # Preserve EA
         res = res._values
-        if squeeze and res.ndim == 1 and len(res) == 1:
+        if res.ndim == 1 and len(res) == 1:
             res = res[0]
     if hasattr(res, 'values') and is_array(res.values):
         res = res.values
     if is_array(res):
         if res.ndim == 0:
             res = res.item()
-        elif squeeze and res.ndim == 1 and len(res) == 1:
+        elif res.ndim == 1 and len(res) == 1:
             res = res[0]
     return res