I don't expect stacked matrices/vectors to be used often, although there
are some areas that might make heavy use of them, so I think we could live
with the simple implementation, it's just a bit of a wart when there is
broadcasting of arrays. Just to be clear, the '@' broadcasting differs from
the dot broadcasting, agreed?
This lack of elegance and unity combined with frankly; a lack of utility,
made me plead @ is a bad idea in the first place; but I guess I lost that
debate...
On Thu, Aug 7, 2014 at 2:00 AM, Charles R Harris
On Wed, Aug 6, 2014 at 5:51 PM, Nathaniel Smith
wrote: On 7 Aug 2014 00:41, "Charles R Harris"
wrote: On Wed, Aug 6, 2014 at 5:33 PM, Nathaniel Smith
wrote: On Thu, Aug 7, 2014 at 12:24 AM, Charles R Harris
wrote: On Wed, Aug 6, 2014 at 4:57 PM, Nathaniel Smith
On Wed, Aug 6, 2014 at 4:32 PM, Charles R Harris
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
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
Another option, already supported to a large extent, is to have row and col classes inheriting from ndarray that add nothing, except for a
wrote: the '@' preserved. 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...
I don't expect stacked matrices/vectors to be used often, although there are some areas that might make heavy use of them, so I think we could live with the simple implementation, it's just a bit of a wart when there is broadcasting of arrays. Just to be clear, the '@' broadcasting differs from the dot broadcasting, agreed?
Chuck
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