REF: Move compute to BinGrouper.result_index_and_ids (#57599)

Author: rhshadrach

pandas/core/groupby/ops.py

@@ -1110,31 +1110,29 @@ def indices(self):
 
  @cache_readonly
  def group_info(self) -> tuple[npt.NDArray[np.intp], int]:
- ngroups = self.ngroups
- rep = np.diff(np.r_[0, self.bins])
-
- rep = ensure_platform_int(rep)
- if ngroups == len(self.bins):
- comp_ids = np.repeat(np.arange(ngroups), rep)
- else:
- comp_ids = np.repeat(np.r_[-1, np.arange(ngroups)], rep)
-
- return (ensure_platform_int(comp_ids), ngroups)
-
- @cache_readonly
- def result_index(self) -> Index:
- if len(self.binlabels) != 0 and isna(self.binlabels[0]):
- return self.binlabels[1:]
-
- return self.binlabels
+ return self.ids, self.ngroups
 
  @cache_readonly
  def codes(self) -> list[npt.NDArray[np.intp]]:
  return [self.ids]
 
  @cache_readonly
  def result_index_and_ids(self):
- return self.result_index, self.group_info[0]
+ result_index = self.binlabels
+ if len(self.binlabels) != 0 and isna(self.binlabels[0]):
+ result_index = result_index[1:]
+
+ ngroups = len(result_index)
+ rep = np.diff(np.r_[0, self.bins])
+
+ rep = ensure_platform_int(rep)
+ if ngroups == len(self.bins):
+ ids = np.repeat(np.arange(ngroups), rep)
+ else:
+ ids = np.repeat(np.r_[-1, np.arange(ngroups)], rep)
+ ids = ensure_platform_int(ids)
+
+ return result_index, ids
 
  @property
  def levels(self) -> list[Index]: