[Numpy-discussion] Syntax Improvement for Array Transpose

[Ralf Gommers]

On Tue, Jun 25, 2019 at 11:02 PM Marten van Kerkwijk <
m.h.vankerkwijk at gmail.com> wrote:

>
> For the names, my suggestion of lower-casing the M in the initial one,
> i.e., `.mT` and `.mH`, so far seemed most supported (and I think we should
> discuss *assuming* those would eventually involve not copying data; let's
> not worry about implementation details).
>

For the record, this is not an implementation detail. It was the consensus
before that `H` is a bad idea unless it returns a view just like `T`:
https://github.com/numpy/numpy/issues/8882


> So, specific items to confirm:
>
> 1) Is this a worthy addition? (certainly, their existence would reduce
> confusion about `.T`... so far, my sense is tentative yes)
>
> 2) Are `.mT` and `.mH` indeed the consensus? [1]
>

I think `H` would be good to revisit *if* it can be made to return a view.
I think a tweak on `T` for >2-D input does not meet the bar for inclusion.

Cheers,
Ralf


> 3) What, if anything, should these new properties do for 0-d and 1-d
> arrays: pass through, change shape, or error? (logically, I think *new*
> properties should never emit warnings: either do something or error).
> - In favour of pass-through: 1-d is a vector `dot` and `matmul` work fine
> with this;
> - In favour of shape change: "m" stands for matrix; can be generous on
> input, but should be strict on output. After all, other code may not make
> the same assumption that 1-d arrays are fine as row and column vectors.
> - In favour of error: "m" stands for matrix and the input is not a matrix!
> Let the user add np.newaxis in the right place, which will make the intent
> clear.
>
>
>
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