[Numpy-discussion] numpy1.2 : make sorts unary ufuncs

Charles R Harris charlesr.harris@gmail....
Sat Apr 19 01:55:49 CDT 2008


On Sat, Apr 19, 2008 at 12:20 AM, Travis E. Oliphant <oliphant@enthought.com>
wrote:

> Charles R Harris wrote:
> > The signature for a ufunc is something like
> >
> > @TYPE@_@kind@(char **args, intp *dimensions, intp *steps, void *func)
> >
> > Which contains all the info necessary to do a sort. Means and other
> > such functions could also be implemented that way.
> I dont' think the ufunc is the right place for this.    Perhaps sorting
> can be viewed however as a "general function" which I'd like to add.
> Maybe, in that case the ufunc could be a special case of the "general
> function" concept.   But, that is the direction I would expect the
> discussion to go.
>
> The ufunc object is a very particular kind of thing.   The 1-d inner
> loop signature is a key part of it, but there is more to it than that.
> I don't see  how the sorting function can be pushed into this concept.
>

Yes, but the inner loop is just something that uses the array values along
that axis to produce another set of values, i.e., it is a vector valued
function of vectors. So is a sort, so is argsort, so is the inner product,
so on and so forth. That's what we have here:

typedef void (*PyUFuncGenericFunction) (char **, npy_intp *, npy_intp *,
void *);

 No difference that I can see. It is the call function in PyUFuncObject that
matters.


> But, there is a case to be made for perhaps figuring out how to merge
> the data-type functions and the ufuncs into one idea that allows for
> better code re-use.
>

I don't think we can get all of them, but I think we can get most.

Chuck
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