From: Raymond Hettinger <rhettinger@users.noreply.github.com>
Date: Sat, 20 Nov 2021 16:04:37 +0000 (-0600)
Subject: bpo-45851: Avoid full sort in statistics.multimode() (#29662)
X-Git-Tag: v3.11.0a3~195
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=04e03f496cf7da48ce4f545b41579d7d45f59ad2;p=thirdparty%2FPython%2Fcpython.git

bpo-45851: Avoid full sort in statistics.multimode() (#29662)

Suggested by Stefan Pochmann.
---

diff --git a/Lib/statistics.py b/Lib/statistics.py
index e67c51709136..4f3ab49b4021 100644
--- a/Lib/statistics.py
+++ b/Lib/statistics.py
@@ -609,9 +609,11 @@ def multimode(data):
     >>> multimode('')
     []
     """
-    counts = Counter(iter(data)).most_common()
-    maxcount, mode_items = next(groupby(counts, key=itemgetter(1)), (0, []))
-    return list(map(itemgetter(0), mode_items))
+    counts = Counter(iter(data))
+    if not counts:
+        return []
+    maxcount = max(counts.values())
+    return [value for value, count in counts.items() if count == maxcount]
 
 
 # Notes on methods for computing quantiles