[Numpy-discussion] ndarray.T2 for 2D transpose

[Sebastian Berg]

On Do, 2016-04-07 at 17:00 +0000, Ian Henriksen wrote:
> 
> 
> On Wed, Apr 6, 2016 at 3:21 PM Nathaniel Smith <njs at pobox.com> wrote:
> >  Can you elaborate on what you're doing that you find verbose and
> > confusing, maybe paste an example? I've never had any trouble like
> > this doing linear algebra with @ or dot (which have similar
> > semantics
> > for 1d arrays), which is probably just because I've had different
> > use
> > cases, but it's much easier to talk about these things with a
> > concrete
> > example in front of us to put everyone on the same page.
> > 
> > -n
> Here's another example that I've seen catch people now and again.
> 
> A = np.random.rand(100, 100)
> b =  np.random.rand(10)
> A * b.T
> 
> In this case the user pretty clearly meant to be broadcasting along
> the rows of A
> rather than along the columns, but the code fails silently. When an
> issue like this
> gets mixed into a larger series of broadcasting operations, the error
> becomes
> difficult to find. This error isn't necessarily unique to beginners
> either. It's a
> common typo that catches intermediate users who know about
> broadcasting
> semantics but weren't keeping close enough track of the
> dimensionality of the
> different intermediate expressions in their code.
> 

Yes, but as noted in my other mail, A @ b.T2 would behave the same as
far as I can see?! Because `@` tries to make logic of 1-D arrays in an
"inner" fashion.

- Sebastian


> Best,
> 
> -Ian Henriksen
> 
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