3 (-@[{:\ -@(|#)}.]) 3 0 7 2 9 1 5 8 4 6
7 1 4
A simpler version (at least for me) of Rich's solution is
3 (,:~@[ {:;._3 ]) 3 0 7 2 9 1 5 8 4 6
7 1 4
R.E. Boss
> -----Oorspronkelijk bericht-----
> Van: Programming <[email protected]>
> Namens 'Mike Day' via Programming
> Verzonden: donderdag 31 oktober 2019 20:02
> Aan: [email protected]
> Onderwerp: Re: [Jprogramming] odds and nths
>
> Unfortunately, Lorenz Koehl wants every item with an odd index, or with an
> index equal to -1 modulo n.
>
> So if
> [q =. 10?10. NB. 3rd call of 10?10, I think
> 3 0 7 2 9 1 5 8 4 6
> odd q NB. Koehl
> 0 2 1 8 6
> 3 nth q NB. Koehl
> 7 1 4
> 3 ({:;._3~ ,:~)~ q NB. Henry Rich
> 7 1 4
> 3(]#~<:@[=|)q NB. R E Boss
> 2 5 8
>
> Henry’s method looks pretty minimal!
> This doesn’t quite work in the general case, but fwiw, anyway:
> _3 {: \ q. NB. !
> 7 1 4 6
>
> Mike
>
> PS I see you’ve just spotted the difference!
>
> Sent from my iPad
>
> > On 31 Oct 2019, at 18:14, R.E. Boss <[email protected]> wrote:
> >
> > And minus another one:
> >
> > 3(]#~<:@[=|)i.8
> > 2 5
> >
> >
> > R.E. Boss
> >
> >
> >> -----Oorspronkelijk bericht-----
> >> Van: Programming <[email protected]>
> >> Namens Raul Miller
> >> Verzonden: donderdag 31 oktober 2019 18:27
> >> Aan: Programming forum <[email protected]>
> >> Onderwerp: Re: [Jprogramming] odds and nths
> >>
> >> One character shorter:
> >>
> >> 3(]#~0=(|#\))i.8
> >> 2 5
> >>
> >> Thanks,
> >>
> >> --
> >> Raul
> >>
> >>> On Thu, Oct 31, 2019 at 12:43 PM Henry Rich <[email protected]>
> wrote:
> >>>
> >>> 3 ({:;._3~ ,:~)~ i. 8
> >>> 2 5
> >>>
> >>> Henry Rich
> >>>
> >>>> On 10/31/2019 12:33 PM, Lorenz Köhl wrote:
> >>>> NB. get items with odd index
> >>>> odd=. ] #~ 0 1 $~ #
> >>>>
> >>>> Generalizing this I got
> >>>>
> >>>> NB. get the nth items
> >>>> nth=. ] #~ (1 ,~ 0 $~ 1 -~ [) $~ [: # ]
> >>>>
> >>>> I bet this is not the shortest version!
> >>>>
> >>>> I tried infix but it includes fret/fill
> >>>>
> >>>> wrong_odd=. [: {: [: |: _2 ]\ ]
> >>>>
> >>>> happy halloween
> >>>>
> >>>> Lo
> >>>> -------------------------------------------------------------------
> >>>> -
> >>>> -- For information about J forums see
> >>>> http://www.jsoftware.com/forums.htm
> >>>
> >>>
> >>> --
> >>> This email has been checked for viruses by AVG.
> >>> https://www.avg.com
> >>>
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> >>> --
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> >> http://www.jsoftware.com/forums.htm
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