On Mon, Mar 16, 2015 at 9:28 AM, Jerome Kieffer <jerome.kief...@esrf.fr> wrote:
> On Mon, 16 Mar 2015 06:56:58 -0700 > Jaime Fernández del Río <jaime.f...@gmail.com> wrote: > > > Dispatching to a different method seems like a no brainer indeed. The > > question is whether we really need to do this in C. > > I need to do both unweighted & weighted histograms and we got a factor 5 > using (simple) cython: > it is in the proceedings of Euroscipy, last year. > http://arxiv.org/pdf/1412.6367.pdf If I read your paper and code properly, you got 5x faster, mostly because you combined the weighted and unweighted histograms into a single search of the array, and because you used an algorithm that can only be applied to equal- sized bins, similarly to the 10x speed-up Robert was reporting. I think that having a special path for equal sized bins is a great idea: let's do it, PRs are always welcome! Similarly, getting the counts together with the weights seems like a very good idea. I also think that writing it in Python is going to take us 80% of the way there: most of the improvements both of you have reported are not likely to be coming from the language chosen, but from the algorithm used. And if C proves to be sufficiently faster to warrant using it, it should be confined to the number crunching: I don;t think there is any point in rewriting argument parsing in C. Also, keep in mind `np.histogram` can now handle arrays of just about **any** dtype. Handling that complexity in C is not a ride in the park. Other functions like `np.bincount` and `np.digitize` cheat by only handling `double` typed arrays, a luxury that histogram probably can't afford at this point in time. Jaime -- (\__/) ( O.o) ( > <) Este es Conejo. Copia a Conejo en tu firma y ayúdale en sus planes de dominación mundial.
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