Hi Joe, Henry touches on this in JforC: Apply On Subsets: Dyad u/.
http://www.jsoftware.com/help/jforc/loopless_code_v_partitions.htm#_Toc191734451 He does a total instead of an append, but I think you'll get the idea. Cheers, bob On Aug 12, 2014, at 3:19 PM, Joe Bogner <[email protected]> wrote: > I've been fiddling with this for 30 minutes and I can't figure it > out... Maybe it's too late in the day > > a=:_2]\'a';1;'b';2;'c';3 > b=:_2]\'c';5;'a';4 > > what verb will produce this? > > ]a,.(4;'';5) > ┌─┬─┬─┐ > │a│1│4│ > ├─┼─┼─┤ > │b│2│ │ > ├─┼─┼─┤ > │c│3│5│ > └─┴─┴─┘ > > > I went down this path: > > ] ((0{"1 b)i.(0{"1 a)) > 1 2 0 > > I figured I could use { and return '' if the index was greater than > the length (e.g., 2 should be '') > > I tried using :: to return '' on index error but I couldn't get that to work > > NB. not what I wanted > ] ((0{"1 b)i.(0{"1 a)) ({ :: ('no'"_)) b > no > > Then I tried using ^: to return '' if the length was greater than # b > > Then I tried writing a explicit verb using if. > > Then I threw in the towel and decided to ask for help since this must > be a common need > > I'm sure I've solved this before but cannot remember how > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
