Mark Bell <mark00b...@googlemail.com> added the comment:
To give two more consequences of `random.choices` using floating point arithmetic: 1) When doing `random.choices([A, B, C], weights=[2**55, 1, 1])` the cumulative weight to bisect for is selected using `floor(random() * (2**55 + 1 + 1 + 0.0))`. Since this is always even, it is impossible for `B` to be chosen. 2) When doing `random.choices([A, B], weights=[2**54, 1])` although the `cum_weights` is [18014398509481984, 18014398509481985] the `total` used by `random.choices` is `cum_weights[-1] + 0.0`. Due to floating point rounding this is 18014398509481984.0 and so is actually smaller than `cum_weights[-1]`. Therefore it is impossible for `B` to be chosen. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue47114> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
