From: Raymond Hettinger <rhettinger@users.noreply.github.com>
Date: Thu, 23 Apr 2026 03:06:56 +0000 (-0500)
Subject: Speed up counting in statistics.fmean() (gh-148875)
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=fbc7676df6256071682f4179818b74ba29f162cd;p=thirdparty%2FPython%2Fcpython.git

Speed up counting in statistics.fmean() (gh-148875)
---

diff --git a/Lib/statistics.py b/Lib/statistics.py
index e635b99f958e..32fcf2313a81 100644
--- a/Lib/statistics.py
+++ b/Lib/statistics.py
@@ -136,7 +136,7 @@ import sys
 
 from fractions import Fraction
 from decimal import Decimal
-from itertools import count, groupby, repeat
+from itertools import compress, count, groupby, repeat
 from bisect import bisect_left, bisect_right
 from math import hypot, sqrt, fabs, exp, erfc, tau, log, fsum, sumprod
 from math import isfinite, isinf, pi, cos, sin, tan, cosh, asin, atan, acos
@@ -195,9 +195,9 @@ def fmean(data, weights=None):
             n = len(data)
         except TypeError:
             # Handle iterators that do not define __len__().
-            counter = count()
-            total = fsum(map(itemgetter(0), zip(data, counter)))
-            n = next(counter)
+            counter = count(1)
+            total = fsum(compress(data, counter))
+            n = next(counter) - 1
         else:
             total = fsum(data)