[Numpy-discussion] stability of numpy.random.RandomState API?

Barry Wark barrywark@gmail....
Thu Nov 6 15:12:34 CST 2008


On Thu, Nov 6, 2008 at 12:09 PM, Robert Kern <robert.kern@gmail.com> wrote:
> On Thu, Nov 6, 2008 at 14:05, Barry Wark <barrywark@gmail.com> wrote:
>> I'm just about to embark on a long-term research project and was
>> planning to use numpy.random to generate stimuli for our experiments.
>> We plan to store only the parameters and RandomState seed for each
>> stimulus and I'm concerned about stability of the API in the long
>> term: will the parameters and random seed we store now work with
>> future versions of numpy.random?
>
> It should. But just in case, make sure you explicitly instantiate
> RandomState objects instead of using the functions in numpy.random.
> That way, should we need to fix some bug that might change the
> results, you can always pull out the current mtrand code and use it
> independently.

That is our working plan, as well as to record the numpy.__version__
which was used to generate the original stimulus. Thanks for the
confirmation.

On a side note, this seems like a potentially big issue for many
scientific users. Perhaps making a policy of keeping incompatible
revisions to  RandomState noted in its documentation (if they ever
come up) would be useful. Even better, a module function or class
method that returns an instance of RandomState as it was at a
particular numpy version:

r = numpy.random.RandomState.from_version(my_numpy_version, seed=None)

Hmm. Sounds like a bit of work. I'll give it a go, if you think this
is a valuable approach.

>
>> I think I recall that there was a
>> change in the random seed format some time around numpy 1.0.
>
> I don't think I changed it after 1.0. Before 1.0, we explicitly warned
> people about API instability.

I believe you. We've been developing this app since before numpy 1.0,
so I'm sure the issue cropped up from data generated pre-1.0.

>
> --
> Robert Kern
>
> "I have come to believe that the whole world is an enigma, a harmless
> enigma that is made terrible by our own mad attempt to interpret it as
> though it had an underlying truth."
>  -- Umberto Eco
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