Jay, thanks for reminding me of the rank operator. I had forgotten about
that one. :-)
Yes, in this case it would definitely do the right thing, but as you
mention it won't allow you to work on other axes.
Regards,
Elias
On 31 March 2014 15:29, Jay Foad <jay.f...@gmail.com> wrote:
> On 31 March 2014 04:51, Elias Mårtenson <loke...@gmail.com> wrote:
> > I keep wanting to be able to apply an axis argument to the ¨ (EACH)
> > operator. I.e, to sort an array rows, I wanted to do:
> >
> > {⍵[⍋⍵]}¨[2] foo
> >
> >
> > Instead, I had to do:
> >
> > ⊃ {⍵[⍋⍵]}¨ ⊂[2] foo
> >
> >
> > Would it make sense to be able to specify an axis number to the the EACH
> > operator as an extension?
>
> Hi Elias,
>
> Have you considered using the Rank operator?
>
> {⍵[⍋⍵]}⍤1(4 3⍴'FEEFIEFOEFUM')
> EEF
> EFI
> EFO
> FMU
>
> There is a bit of tension in APL between these two different ways of
> solving the same kinds of problem: primitives-with-axis, and the Rank
> operator.
>
> - Primitives-with-axis are a bit ad hoc. Every primitive interprets
> the axis specification in a different way, and some primitives (like
> Each) don't support it at all.
>
> - By contrast, the Rank operator is completely uniform and applies to
> all functions.
>
> - But the Rank operator restricts you to dividing the argument up
> along the leading axes. (Some would argue that this restriction is a
> good thing.) E.g. you can use it to sort each row of a matrix, but not
> to sort each column.
>
> Jay.
>
