Hi, that's my version with i:
seq=: monad : '{.y+/(-@>:@| {. i:) (-/|.y)'
Mario
Devon McCormick <[email protected]> schrieb am So., 8. Apr. 2018, 01:52:
> Thanks to everyone who answered - there were a few that were just what I
> needed.
>
> On Sat, Apr 7, 2018 at 6:48 AM, 'Pascal Jasmin' via Programming <
> [email protected]> wrote:
>
> > there is also,
> >
> > iota =: i. : (+ i.)
> >
> >
> > 3 iota 5
> > 3 4 5 6 7
> >
> > ([ iota >:@-~)/ 3 7
> > 3 4 5 6 7
> >
> > 3 iota _5
> > 7 6 5 4 3
> >
> >
> > ________________________________
> > From: Joe Bogner <[email protected]>
> > To: [email protected]
> > Sent: Friday, April 6, 2018 3:50 PM
> > Subject: Re: [Jprogramming] Expression to generate sequ
> >
> >
> >
> > Lightly tested and non-optimized and ugly, but seems to work!
> >
> > genseq=:({: + i.@:>:@:-/)@]
> >
> > seq =: (] (>/@[ \:~@]^:[ genseq) \:~) f.
> >
> >
> > ] (>/@[ \:~@]^:[ ({: + i.@:>:@:-/)@]) \:~
> >
> >
> > seq 3 7 3 4 5 6 7 seq 7 3 7 6 5 4 3
> >
> >
> >
> >
> > On Fri, Apr 6, 2018 at 3:23 PM, Devon McCormick <[email protected]>
> > wrote:
> >
> > > Hi -
> > >
> > > I'm working with selecting sequential items from a vector given a
> > starting
> > > and an ending point as a pair of integers. If we assume we always get
> > the
> > > pair as (lesser, greater), something like this suffices:
> > >
> > > seq=: {. + [: i. [: >: -~/
> > > seq 3 7
> > > 3 4 5 6 7
> > >
> > > However, if our assumption about the order of our points is violated,
> we
> > > get nonsense:
> > >
> > > seq 7 3
> > > 7 8 9
> > >
> > > Just for robustness, how could we write a version of "seq" that would
> > > return the sequence in reverse order in this latter case, i.e. give the
> > > proper sequence from seven to three: 7 6 5 4 3 ?
> > >
> > > I generalized the "seq" verb to remove the ordering assumption: my idea
> > was
> > > to generate the ascending sequence, then flip it if >/y is true. I
> tried
> > > this with "agenda" but am not sure how to get it to work on one thing -
> > the
> > > ascending vector - on the basis of comparison of another thing - the
> pair
> > > of integers.
> > >
> > > I did achieve this using the "power" conjunction:
> > >
> > > seq=: 3 : '|.^:(>/y)](<./ + [: i. [: >: >./ - <./) y'
> > > seq 3 7
> > > 3 4 5 6 7
> > > seq 7 3
> > > 7 6 5 4 3
> > >
> > > Does anyone have any ideas for a more elegant, preferably tacit,
> > solution?
> > >
> > > Thanks,
> > >
> > > Devon
> > > --
> > >
> > > Devon McCormick, CFA
> > >
> > > Quantitative Consultant
> > > ----------------------------------------------------------------------
> > > For information about J forums see http://www.jsoftware.com/forums.htm
> >
> > ----------------------------------------------------------------------
> > For information about J forums see http://www.jsoftware.com/forums.htm
> > ----------------------------------------------------------------------
> > For information about J forums see http://www.jsoftware.com/forums.htm
> >
>
>
>
> --
>
> Devon McCormick, CFA
>
> Quantitative Consultant
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
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