CLN: assorted (#46181)

Author: jbrockmendel

doc/source/whatsnew/v1.5.0.rst

@@ -295,6 +295,7 @@ Performance improvements
 - Performance improvement in :meth:`MultiIndex.get_locs` (:issue:`45681`, :issue:`46040`)
 - Performance improvement in :func:`merge` when left and/or right are empty (:issue:`45838`)
 - Performance improvement in :meth:`DataFrame.join` when left and/or right are empty (:issue:`46015`)
+- Performance improvement in :func:`factorize` (:issue:`46109`)
 - Performance improvement in :class:`DataFrame` and :class:`Series` constructors for extension dtype scalars (:issue:`45854`)
 -
 

pandas/_libs/groupby.pyi

@@ -56,7 +56,7 @@ def group_add(
     values: np.ndarray,  # ndarray[complexfloating_t, ndim=2]
     labels: np.ndarray,  # const intp_t[:]
     min_count: int = ...,
-    datetimelike: bool = ...,
+    is_datetimelike: bool = ...,
 ) -> None: ...
 def group_prod(
     out: np.ndarray,  # floating[:, ::1]
@@ -104,6 +104,8 @@ def group_last(
     counts: np.ndarray,  # int64_t[::1]
     values: np.ndarray,  # ndarray[rank_t, ndim=2]
     labels: np.ndarray,  # const int64_t[:]
+    mask: npt.NDArray[np.bool_] | None,
+    result_mask: npt.NDArray[np.bool_] | None,
     min_count: int = ...,  # Py_ssize_t
 ) -> None: ...
 def group_nth(