GH-100425: Note improved commutativity in sum(). by rhettinger · Pull Request #107785 · python/cpython (original) (raw)

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rhettinger

Contributor

@rhettinger rhettinger commented

Aug 8, 2023

•

edited by github-actionsbot

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@rhettinger

@rhettinger

Script to demonstrate the improvement:

from random import random
from itertools import permutations

n = 4
trials = 100

errors = 0
for i in range(trials):
    example = [random() for i in range(n)]
    if len(set(map(sum, permutations(example)))) != 1:
        errors += 1
        print(i, sorted(example))
print(f'{errors / trials * 100.0=}%')

Formerly there was a 63% error rate. Now it is zero.

@miss-islington

Thanks @rhettinger for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖

@bedevere-bot

miss-islington pushed a commit to miss-islington/cpython that referenced this pull request

Aug 8, 2023

@rhettinger @miss-islington

(cherry picked from commit aab6f71)

Co-authored-by: Raymond Hettinger rhettinger@users.noreply.github.com