On So, 2016-09-11 at 21:21 +0000, Pauli Virtanen wrote: > Hi, > > In the end some further API additions turn out to appear needed: >
Very nice :). > * NPY_ITER_COPY_IF_OVERLAP, NPY_ITER_OVERLAP_NOT_SAME > flags for NpyIter_New. > > * New API function PyArray_MapIterArrayCopyIfOverlap, > as ufunc.at needs to check overlaps for index arrays > before constructing iterators, and the parsing is done > in multiarray. I think here Nathaniels point might be right. It could be we can assume that copying is always fine, there is probably only one or two downstream projects using this function, plus it seems harder to create abusing structures that actually do something useful. It was only exposed for usage in `ufunc.at` if I remember right. I know theano uses it though, but not sure about anyone else, maybe numba. On the other hand.... It is not the worst API clutter in history. > > Continuation here: https://github.com/numpy/numpy/pull/8043 > > > > Wed, 07 Sep 2016 18:02:59 +0200, Sebastian Berg kirjoitti: > > > > > Hi all, > > > > Pauli just opened a nice pull request [1] to add overlap detection > > to > > the new iterator, this means adding a new iterator flag: > > > > `NPY_ITER_COPY_IF_OVERLAP` > > > > If passed to the iterator (also exposed in python), the iterator > > will > > copy the operands such that reading and writing should only occur > > for > > identical operands. For now this is implemented by always copying > > the > > output/writable operand (this could be improved though, so I would > > not > > say its fixed API). > > > > Since adding this flag is new API, please feel free to suggest > > other > > names/approaches or even decline the change ;). > > > > > > This is basically a first step, which should be easily followed by > > adding overlap detection to ufuncs, removing traps such as the well > > (or > > not so well known) `a += a.T`. Other parts of numpy may follow one > > by > > one. > > > > The work is based on his older awesome new memory overlap detection > > implementation. > > > > If there are no comments, I will probably merge it very soon, so we > > can > > look at the follow up things. > > > > - Sebastian > > > > > > [1] https://github.com/numpy/numpy/ > pull/8026_______________________________________________ > > > > NumPy-Discussion mailing list NumPy-Discussion@scipy.org > > https://mail.scipy.org/mailman/listinfo/numpy-discussion > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > https://mail.scipy.org/mailman/listinfo/numpy-discussion
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