I agree that this solution is elegant, but for a large data set I assume that Raul's idea of prepending and then dropping 3 elements would be more efficient. Don't you, too?
(<@}./.~ *) _1 0 1,data On Thu, Sep 23, 2010 at 8:26 AM, R.E. Boss <r.e.b...@planet.nl> wrote: > One of the more elegant solutions is > > ((/:&(* </. ])) *) data > +---------------+---+-----+ > |_3 _1 _10 _2 _4|0 0|1 1 6| > +---------------+---+-----+ > > > R.E. Boss > > >> -----Oorspronkelijk bericht----- >> Van: programming-boun...@jsoftware.com [mailto:programming- >> boun...@jsoftware.com] Namens Marshall Lochbaum >> Verzonden: woensdag 22 september 2010 23:57 >> Aan: Programming forum >> Onderwerp: Re: [Jprogramming] Classification problem >> >> It looks to me like the most terse way is >> ((</. /: ~...@[)~ f) data >> >> Although this computes the nub twice, unlike some earlier solutions. >> >> Marshall >> >> ________________________________________ >> From: programming-boun...@jsoftware.com [programming- >> boun...@jsoftware.com] On Behalf Of Raul Miller [rauldmil...@gmail.com] >> Sent: Wednesday, September 22, 2010 3:29 PM >> To: Programming forum >> Subject: Re: [Jprogramming] Classification problem >> >> Note, if * is the universe of interesting >> functions (if it does not need to be generic) then >> I would be tempted to use a variation on Dan's >> second suggestion: >> >> (<@}./.~ *) _1 0 1,data >> >> Note that this also preserves the relative >> ordering of the data items. >> >> -- >> Raul >> ---------------------------------------------------------------------- >> 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 > -- (B=) <-----my sig Brian Schott ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
