Mike, Thanks for reminding me that there's a more concise way to create arrays of random numbers. I should have realized that.
Skip Skip Cave Cave Consulting LLC On Fri, Sep 1, 2017 at 3:03 AM, 'Mike Day' via Programming < programm...@jsoftware.com> wrote: > I forgot to point out earlier that > > 6 12 $ ? 72 $ 10 > > may be defined more succinctly as > > ? 6 12 $ 10 > > FWIW, I had a look at an alternative approach, working on the union of > all rows: > > union =: ~.@:, NB. ie nub of the ravel > > rix =: (] #~ */@:(e."1)~) union NB. another row intersection verb > > > It works, but is more verbose, uses more memory and more cp time for the > limited > > cases I've explored. > > > Mike > > > > > > On 01/09/2017 08:40, 'Mike Day' via Programming wrote: > >> The main requirement is to obtain the set-intersection of the rows: >> >> rowintersection =: ([-.-.)&~./ >> >> (The &~. isn't essential, but it will save space for large arrays with >> significant repetition.) >> >> >> (Drafting this, I see Raul's beaten me to it, though he didn't include >> the &~. !!!) >> >> >> Also, >> >> colintersection =: rowintersection@:|: >> >> >> >> Cheers, >> >> >> Mike >> >> >> >> >> On 01/09/2017 07:48, Skip Cave wrote: >> >>> ]a =: 6 12$ ?72$10 >>> >> >> >> >> --- >> This email has been checked for viruses by Avast antivirus software. >> https://www.avast.com/antivirus >> ---------------------------------------------------------------------- >> 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
