random.Random.sample bug when counts is not None

[jonanifranco]

BPO	42944
Nosy	@rhettinger, @miss-islington, @jonanifranco
PRs	bpo-42944 Fix Random.sample when counts is not None #24235 [3.9] bpo-42944 Fix Random.sample when counts is not None (GH-24235) #24243

^{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 = 'https://github.com/rhettinger'
closed_at = <Date 2021-01-18.18:36:36.628>
created_at = <Date 2021-01-16.22:58:54.655>
labels = ['type-bug', 'library', '3.9', '3.10']
title = 'random.Random.sample bug when counts is not None'
updated_at = <Date 2021-01-18.18:36:36.628>
user = 'https://github.com/jonanifranco'

bugs.python.org fields:

activity = <Date 2021-01-18.18:36:36.628>
actor = 'rhettinger'
assignee = 'rhettinger'
closed = True
closed_date = <Date 2021-01-18.18:36:36.628>
closer = 'rhettinger'
components = ['Library (Lib)']
creation = <Date 2021-01-16.22:58:54.655>
creator = 'jonfranco'
dependencies = []
files = []
hgrepos = []
issue_num = 42944
keywords = ['patch']
message_count = 6.0
messages = ['385152', '385153', '385158', '385209', '385215', '385216']
nosy_count = 3.0
nosy_names = ['rhettinger', 'miss-islington', 'jonfranco']
pr_nums = ['24235', '24243']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue42944'
versions = ['Python 3.9', 'Python 3.10']

[jonanifranco]

Hello,

If I am reading right, random.Random.sample method has a bug if counts is not None.

Line 482 (of master):
"""
selections = sample(range(total), k=k)
"""
this is calling the module function 'sample' and not the instance method.

IMO this line should be:
"""
selections = self.sample(range(total), k=k)
"""

Python 3.9.1 (default, Dec 11 2020, 14:32:07) 
[GCC 7.3.0] :: Anaconda, Inc. on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from random import Random
>>> r = Random()
>>> r.seed('bug')
>>> r.sample(range(50), 5, counts=range(1,51))
[34, 39, 31, 42, 38]
>>> r.seed('bug')
>>> r.sample(range(50), 5, counts=range(1,51))
[39, 11, 3, 12, 29]  <====== this should be [34, 39, 31, 42, 38]
>>> r.seed('nobug')
>>> r.sample(range(50), 5)
[0, 30, 23, 17, 49]
>>> r.seed('nobug')
>>> r.sample(range(50), 5)
[0, 30, 23, 17, 49]

Regards,
Jon FRANCO

[rhettinger]

Would you like to submit a PR for this?

[jonanifranco]

PR submitted.
Let me know if I missed something, this is also my first PR.
Regards.

[rhettinger]

New changeset f7b5bac by jonanifranco in branch 'master':
bpo-42944 Fix Random.sample when counts is not None (GH-24235)
f7b5bac

[rhettinger]

New changeset a90539f by Miss Islington (bot) in branch '3.9':
bpo-42944 Fix Random.sample when counts is not None (GH-24235) (GH-24243)
a90539f

[rhettinger]

Thanks for the report and the PR.