On Sun, Jun 3, 2018 at 6:01 PM <josef.p...@gmail.com> wrote: > > > On Sun, Jun 3, 2018 at 8:36 PM, Robert Kern <robert.k...@gmail.com> wrote: > >> On Sun, Jun 3, 2018 at 4:35 PM Eric Wieser <wieser.eric+nu...@gmail.com> >> wrote: >> >>> You make a bunch of good points refuting reproducible research as an >>> argument for not changing the random number streams. >>> >>> However, there’s a second use-case you don’t address - unit tests. For >>> better or worse, downstream, or even our own >>> <https://github.com/numpy/numpy/blob/c4813a9/numpy/core/tests/test_multiarray.py#L5093-L5108>, >>> unit tests use a seeded random number generator as a shorthand to produce >>> some arbirary array, and then hard-code the expected output in their tests. >>> Breaking stream compatibility will break these tests. >>> >> By the way, the reason that I didn't mention this use case as a >> motivation in the Status Quo section because, as I reviewed my mail >> archive, this wasn't actually a motivating use case for the policy. It's >> certainly a use case that developed once we did make these >> (*cough*extravagant*cough*) guarantees, though, as people started to rely >> on it, and I hope that my StableRandom proposal addresses it to your >> satisfaction. I could add some more details about that history if you >> think it would be useful. >> > > I don't think that's accurate. > The unit tests for stable random numbers were added when Enthought > silently changed the normal random numbers and we got messages from users > that the unit tests fail and they cannot reproduce our results. > > 6/12/10 > [SciPy-Dev] seeded randn gets different values on osx > > (I don't find an online copy, this is from my own mail archive) >
The policy was in place Nov 2008. -- Robert Kern
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