On 7 Aug 2014 00:41, "Charles R Harris" <charlesr.har...@gmail.com> wrote: > > On Wed, Aug 6, 2014 at 5:33 PM, Nathaniel Smith <n...@pobox.com> wrote: >> >> On Thu, Aug 7, 2014 at 12:24 AM, Charles R Harris >> <charlesr.har...@gmail.com> wrote: >> > >> > On Wed, Aug 6, 2014 at 4:57 PM, Nathaniel Smith <n...@pobox.com> wrote: >> >> >> >> On Wed, Aug 6, 2014 at 4:32 PM, Charles R Harris >> >> <charlesr.har...@gmail.com> wrote: >> >> > Should also mention that we don't have the ability to operate on stacked >> >> > vectors because they can't be identified by dimension info. One >> >> > workaround >> >> > is to add dummy dimensions where needed, another is to add two flags, >> >> > row >> >> > and col, and set them appropriately. Two flags are needed for backward >> >> > compatibility, i.e., both false is a traditional array. >> >> >> >> It's possible I could be convinced to like this, but it would take a >> >> substantial amount of convincing :-). It seems like a pretty big >> >> violation of orthogonality/"one obvious way"/etc. to have two totally >> >> different ways of representing row/column vectors. >> >> >> > >> > The '@' operator supports matrix stacks, so it would seem we also need to >> > support vector stacks. The new addition would only be effective with the '@' >> > operator. The main problem I see with flags is that adding them would >> > require an extensive audit of the C code to make sure they were preserved. >> > Another option, already supported to a large extent, is to have row and col >> > classes inheriting from ndarray that add nothing, except for a possible new >> > transpose type function/method. I did mock up such a class just for fun, and >> > also added a 'dyad' function. If we really don't care to support stacked >> > vectors we can get by without adding anything. >> >> It's possible you could convince me that this is a good idea, but I'm >> starting at like -0.95 :-). Wouldn't it be vastly simpler to just have >> np.linalg.matvec, matmat, vecvec or something (each of which are >> single-liners in terms of @), rather than deal with two different ways >> of representing row/column vectors everywhere? >> > > Sure, but matvec and vecvec would not be supported by '@' except when vec was 1d because there is no way to distinguish a stack of vectors from a matrix or a stack of matrices.
Yes. But @ can never be magic - either people will have to write something extra to flip these flags on their array objects, or they'll have to write something extra to describe which operation they want. @ was never intended to cover every case, just the simple-but-super-common ones that dot covers, plus a few more (simple broadcasting). We have np.add even though + exists too... -n
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