New submission from Piotr Jurkiewicz <piotr.jerzy.jurkiew...@gmail.com>:
Function random.choices(), which appeared in Python 3.6, allows to perform weighted random sampling with replacement. Function random.sample() performs random sampling without replacement, but cannot do it weighted. I propose to enhance random.sample() to perform weighted sampling. That way all four possibilities will be supported: - non-weighted sampling with replacement: random.choices(..., weights=None) (exists) - weighted sampling with replacement: random.choices(..., weights=weights) (exists) - non-weighted sampling without replacement: random.sample(..., weights=None) (exists) - weighted sampling without replacement: random.sample(..., weights=weights) (NEW) Rationale: Weighted sampling without replacement is a popular problem. There are lot of questions on StackOverflow and similar sites how to implement it. Unfortunately, many proposed solutions are wrong, for example: https://stackoverflow.com/a/353510/2178047 https://softwareengineering.stackexchange.com/a/233552/161807 or have excessive computational complexity (e.g. quadratic). There are lot of suggestions to use numpy.random.choice() to do that, which supports all four possibilities with a single function: numpy.random.choice(a, size=None, replace=True, p=None) But of course this is an overkill to install numpy just to do that. I think that this should be possible with stdlib, without the need to implement it by yourself or to install numpy. Especially, that it can be implemented in 2 lines (plus 4 lines of error checking), as you can see in the PR. ---------- components: Library (Lib) messages: 322367 nosy: piotrjurkiewicz priority: normal severity: normal status: open title: Weighted random.sample() (weighted sampling without replacement) type: enhancement _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue34227> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
