If such an extension was to be implemented I think it would make sense
to have similar arguments work with I. {. {. as well. Current behavior
could be left as a convenience/back compatibility.
Sent from my iPod - excuse terseness and typos.
- joey
On Dec 16, 2009, at 10:41, Roger Hui <[email protected]> wrote:
> The extension can be more readily accommodated (i.e.,
> with backward compatibility) if the left argument were boxed.
> Likewise, if we were designing from scratch (which we are not),
> we would be tempted to box the left arguments of the dyads |. {. }. .
>
>
>
> ----- Original Message -----
> From: Dan Bron <[email protected]>
> Date: Wednesday, December 16, 2009 9:59
> Subject: [Jprogramming] Proposed extension to A. (incompatible)
> To: 'Programming forum' <[email protected]>
>
>> I would like to propose an extension to dyad
>> A. Specifically, I would like dyad A. to
>> interpret left-arguments in a way similar
>> to |. and {. , where each atom
>> of x corresponds to an axis of
>> y . For example, with the new
>> definition, the phrase (0
>> _1 A. i. 4 5) would reverse the columns of y, yielding the
>> same results as (_1 A.&.|: i. 4 5) does with the
>> current definition.
>> Similar statements apply to higher dimensions; I can post a
>> model (using |:) if that's helpful.
>>
>> Of course, right now, the ranks of dyad A. are
>> 0 _ . The new definition of
>> A. would require them to be 1
>> _ , so
>> extension is not backwards compatible. But because of the
>> way A. is typically used, I doubt it would break
>> much code in practice.
>> Furthermore, the fix is trivial; substitute A."_ 0
>> _ for all uses of A.
>>
>> I believe the extension would be useful; more and more I find
>> myself wanting direct access non-leading axes of an array, and I now
>> make heavy use of (boxes <;.n y), (list {. y),
>> (list |. y) etc. This extension to
>> A. would make a nice companion to another
>> proposal I made:
>> http://www.jsoftware.com/jwiki/System/Interpreter/Requests#redefineu.3B.0y
>> .
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