Description

rhettinger

opened on May 1, 2020

Issue body actions

BPO	40465
Nosy	@tim-one, @rhettinger, @vstinner, @serhiy-storchaka, @hugovk
PRs	bpo-40465: Deprecate the optional argument to random.shuffle(). #19867 bpo-40465: Remove random module features deprecated in 3.9 #25874 bpo-40465: Document random module changes in 3.11 What's new #31818

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2020-05-02.23:49:03.587>
created_at = <Date 2020-05-01.08:31:41.792>
labels = ['type-bug', 'library', '3.9']
title = 'Deprecate the optional *random* argument to random.shuffle()'
updated_at = <Date 2022-03-24.13:29:22.965>
user = 'https://github.com/rhettinger'

bugs.python.org fields:

activity = <Date 2022-03-24.13:29:22.965>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2020-05-02.23:49:03.587>
closer = 'rhettinger'
components = ['Library (Lib)']
creation = <Date 2020-05-01.08:31:41.792>
creator = 'rhettinger'
dependencies = []
files = []
hgrepos = []
issue_num = 40465
keywords = ['patch']
message_count = 8.0
messages = ['367826', '367828', '367948', '370417', '370418', '415418', '415940', '415941']
nosy_count = 5.0
nosy_names = ['tim.peters', 'rhettinger', 'vstinner', 'serhiy.storchaka', 'hugovk']
pr_nums = ['19867', '25874', '31818']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue40465'
versions = ['Python 3.9']

Activity

1. rhettinger commented on May 1, 2020

   

   rhettinger

   on May 1, 2020

   ContributorAuthor

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   shuffle(x, random=None) ⟼ shuffle(x)

   AFAICT, no one ever uses the optional parameter, nor would they have a valid reason to do so. It is an ancient API oddity and is inconsistent with the other methods in the module. I've long been annoyed by it and would like to see it cleaned-up before I retire ;-)

   https://docs.python.org/3/library/random.html#random.shuffle
2. rhettinger

   added

   3.9 (EOL)end of lifeend of life

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on May 1, 2020
3. serhiy-storchaka commented on May 1, 2020

   

   serhiy-storchaka

   on May 1, 2020

   Member

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   +1
4. rhettinger commented on May 2, 2020

   

   rhettinger

   on May 2, 2020

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   New changeset 190fac9 by Raymond Hettinger in branch 'master':
   bpo-40465: Deprecate the optional argument to random.shuffle(). (bpo-19867)
   190fac9
5. rhettinger

   closed this as completedon May 2, 2020
6. rhettinger

   closed this as completedon May 2, 2020
7. asottile commented on May 31, 2020

   

   asottilemannequin

   on May 31, 2020

   Mannequin

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   pre-commit uses this to do deterministic shuffling, please don't remove this

   pre-commit/pre-commit#1479
8. serhiy-storchaka commented on May 31, 2020

   

   serhiy-storchaka

   on May 31, 2020

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   Raymond, could you please add an entry in What's New?
9. hugovk commented on Mar 17, 2022

   

   hugovk

   on Mar 17, 2022

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   #75999 adds an entry to What's New in 3.11.
10. serhiy-storchaka commented on Mar 24, 2022

    

    serhiy-storchaka

    on Mar 24, 2022

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    New changeset 12c0012 by Tomáš Hrnčiar in branch 'main':
    bpo-40465: Document random module changes in 3.11 What's new (bpo-31818)
    12c0012
11. vstinner commented on Mar 24, 2022

    

    vstinner

    on Mar 24, 2022

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    commit 70a071d
    Author: Raymond Hettinger <[email protected]>
    Date: Tue May 4 01:55:40 2021 -0700

    bpo-40465: Remove random module features deprecated in 3.9 (GH-25874)
    
12. ezio-melotti

    transferred this issue fromon Apr 10, 2022
13. exarkun

    added a commit that references this issue on Feb 13, 2023

    Remove the explicit `random` parameter from `setlist.shuffle`

    f6407d7
14. shaperilio commented on Aug 23, 2023

    

    shaperilio

    on Aug 23, 2023

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    AFAICT, no one ever uses the optional parameter, nor would they have a valid reason to do so. It is an ancient API oddity and is inconsistent with the other methods in the module. I've long been annoyed by it and would like to see it cleaned-up before I retire ;-)

    Wow, what a bold statement 🤣. We were using it. Hope you're enjoying retirement.

    Can someone help me understand the motivation for this? I keep clicking on links trying to figure it out if there was a bug associated with this, but I'm not familiar with the issue tracking here.

    Reacted by Jan Kaliszewski
15. serhiy-storchaka commented on Aug 23, 2023

    

    serhiy-storchaka

    on Aug 23, 2023

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    1. It complicated the code.
    2. When that argument was specified, the result was less random.
    3. The design just looked wrong.

    Reacted by Tim Peters
16. tim-one commented on Aug 23, 2023

    

    tim-one

    on Aug 23, 2023

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    The default implementation of shuffle() stopped using random() long ago - it switched to a method avoiding floats entirely, and also avoiding the slight statistical biases the come with using floats for this.

    So if you passed random= after that change, it went back to using the older - different & inherently biased - algorithm.

    Keeping a worse algorithm in the code base was a Bad Idea on the face of it, especially given that nobody looking at this knew of anyone actually using the optional argument.

    In the very early days, Python used the feeble (by current standards) Wichmann–Hill generator. Then there was far more user interest in replacing it with something better, even if slower. For the far fewer users who still care about that, there's a documented way to subclass Random now to use whatever other underlying generator you like better, and in a way that affects all the methods (not just shuffle()) building on the underlying generator.

    Reacted by Emilio Graff and Arlo Faria

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