[Numpy-discussion] Backwards-incompatible improvements to numpy.random.RandomState

Daπid davidmenhur at gmail.com
Mon May 25 07:14:08 EDT 2015


On 24 May 2015 at 22:30, Sturla Molden <sturla.molden at gmail.com> wrote:

> Personally I think we should only make guarantees about the data types,
> array shapes, and things like that, but not about the values. Those who
> need a particular version of NumPy for exact reproducibility should
> install the version of Python and NumPy they need. That is why virtual
> environments exist.
>

But there is a lot of legacy code out there that doesn't specify the
version required; and in most cases the original author cannot even be
asked.

Tests are a particularly annoying case. For example, when testing an
algorithm, is usually a good practice to record the number of iterations as
well as the result; consider it an early warning that we have changed
something we possibly didn't mean to, even if the result is correct. If we
want to support several NumPy versions, and the algorithm has any
randomness, the tests would have to be duplicated, or find a seed that
gives the exact same results. Thus, keeping different versions lets us
compare the results against the old API, without needing to duplicate the
tests. A lot less people will get annoyed.


/David.
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