From 63a91d0992b5f2837dc028d1bab34e659535b6b4 Mon Sep 17 00:00:00 2001
From: MeeseeksMachine <39504233+meeseeksmachine@users.noreply.github.com>
Date: Wed, 16 Nov 2022 10:59:43 +0100
Subject: [PATCH] Backport PR #49676 on branch 1.5.x (REGR: Remove groupby's
__getattribute__ for nth) (#49705)
* Backport PR #49676: REGR: Remove groupby's __getattribute__ for nth
Co-authored-by: Richard Shadrach <45562402+rhshadrach@users.noreply.github.com>
---
doc/source/whatsnew/v1.5.2.rst | 1 +
pandas/core/groupby/groupby.py | 27 ++++++++++++---------------
pandas/core/groupby/indexing.py | 4 ++--
3 files changed, 15 insertions(+), 17 deletions(-)
diff --git a/doc/source/whatsnew/v1.5.2.rst b/doc/source/whatsnew/v1.5.2.rst
index 446235d1656dc..540ca2b12165c 100644
--- a/doc/source/whatsnew/v1.5.2.rst
+++ b/doc/source/whatsnew/v1.5.2.rst
@@ -18,6 +18,7 @@ Fixed regressions
- Fixed regression in :meth:`DataFrame.plot` preventing :class:`~matplotlib.colors.Colormap` instance
from being passed using the ``colormap`` argument if Matplotlib 3.6+ is used (:issue:`49374`)
- Fixed regression in :func:`date_range` returning an invalid set of periods for ``CustomBusinessDay`` frequency and ``start`` date with timezone (:issue:`49441`)
+- Fixed performance regression in groupby operations (:issue:`49676`)
-
.. ---------------------------------------------------------------------------
diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index 66c459b90a999..98df2423614d3 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -982,15 +982,6 @@ def __getattr__(self, attr: str):
f"'{type(self).__name__}' object has no attribute '{attr}'"
)
- def __getattribute__(self, attr: str):
- # Intercept nth to allow both call and index
- if attr == "nth":
- return GroupByNthSelector(self)
- elif attr == "nth_actual":
- return super().__getattribute__("nth")
- else:
- return super().__getattribute__(attr)
-
@final
def _make_wrapper(self, name: str) -> Callable:
assert name in self._apply_allowlist
@@ -3015,14 +3006,13 @@ def backfill(self, limit=None):
)
return self.bfill(limit=limit)
- @final
+ # https://github.com/python/mypy/issues/1362
+ # Mypy does not support decorated properties
+ @final # type: ignore[misc]
+ @property
@Substitution(name="groupby")
@Substitution(see_also=_common_see_also)
- def nth(
- self,
- n: PositionalIndexer | tuple,
- dropna: Literal["any", "all", None] = None,
- ) -> NDFrameT:
+ def nth(self) -> GroupByNthSelector:
"""
Take the nth row from each group if n is an int, otherwise a subset of rows.
@@ -3125,6 +3115,13 @@ def nth(
1 1 2.0
4 2 5.0
"""
+ return GroupByNthSelector(self)
+
+ def _nth(
+ self,
+ n: PositionalIndexer | tuple,
+ dropna: Literal["any", "all", None] = None,
+ ) -> NDFrameT:
if not dropna:
with self._group_selection_context():
mask = self._make_mask_from_positional_indexer(n)
diff --git a/pandas/core/groupby/indexing.py b/pandas/core/groupby/indexing.py
index be7b7b3369e89..750097b403f26 100644
--- a/pandas/core/groupby/indexing.py
+++ b/pandas/core/groupby/indexing.py
@@ -297,7 +297,7 @@ def __call__(
n: PositionalIndexer | tuple,
dropna: Literal["any", "all", None] = None,
) -> DataFrame | Series:
- return self.groupby_object.nth_actual(n, dropna)
+ return self.groupby_object._nth(n, dropna)
def __getitem__(self, n: PositionalIndexer | tuple) -> DataFrame | Series:
- return self.groupby_object.nth_actual(n)
+ return self.groupby_object._nth(n)