Wow, great! I'm excited to try this. I think your patch significantly
increases the extendability of numpy.
Is the C-API exposed currently? Can you use the API from Cython (meaning is
the numpy.pxd file updated)?
On Tue, Jan 4, 2011 at 12:04 PM, Mark Wiebe <mwwi...@gmail.com> wrote:
> On Sat, Jan 1, 2011 at 11:23 AM, John Salvatier <jsalv...@u.washington.edu
> > wrote:
>
>> This thread is a bit old, but since it's not possible to use the C-API is
>> possible to accomplish this same thing with the Python API?
>>
>
> I've committed Python exposure for nested iteration to the new_iterator
> branch. In doing so, I also changed the mechanism in C. I found that it
> was simpler to expose to Python if I added a Reset function which gives new
> base data pointers, and this also simplifies C code using nested iterators.
>
> The Python code
>
> a = arange(2).reshape(2,1)
> b = arange(3).reshape(1,3)
>
> i, j = np.nested_iters([a,b], [[0],[1]])
> for x in i:
> print "inner:"
> for y in j:
> print y[0], y[1]
>
>
> gives
>
> inner:
> 0 0
> 0 1
> 0 2
> inner:
> 1 0
> 1 1
> 1 2
>
>
> and C code for nested iteration looks something like this:
>
> NpyIter *iter1, *iter1;
> NpyIter_IterNext_Fn iternext1, iternext2;
> char **dataptrs1;
>
> /*
> * With the exact same operands, no copies allowed, and
> * no axis in op_axes used both in iter1 and iter2.
> * Buffering may be enabled for iter2, but not for iter1.
> */
> iter1 = ...; iter2 = ...;
>
> iternext1 = NpyIter_GetIterNext(iter1);
> iternext2 = NpyIter_GetIterNext(iter2);
> dataptrs1 = NpyIter_GetDataPtrArray(iter1);
>
> do {
> NpyIter_ResetBasePointers(iter2, dataptrs1);
> do {
> /* Use the iter2 values */
> } while (iternext2(iter2));
> } while (iternext1(iter1));
>
> Cheers,
> Mark
>
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