Thanks! I ended up doing that. I'm almost glad to learn that there was no secret feature that I didn't know about. :-)
Regards, Elias On 3 Aug 2014 12:37, "David B. Lamkins" <[email protected]> wrote: > Assuming you want a ravel of the elements under the mask: > > a←2 3⍴1 2 3 4 1 2 > b←2 3⍴0 0 1 0 0 0 > a > 1 2 3 > 4 1 2 > b > 0 0 1 > 0 0 0 > (,b)/,a > 3 > > > On Sun, 2014-08-03 at 00:12 +0800, Elias Mårtenson wrote: > > Here's a problem I've had on multiple occasions, and I have yet to > > figure out a nice generic way of dealing with it. > > > > > > For a one-dimensional array, I can easily select elements based on a > > bitmap: > > > > > > 0 0 1 0 0 0/⍳6 > > 3 > > > > > > Sometimes I want to do the same from a two (or more) dimensional > > array: > > > > > > a > > 1 2 3 > > 4 1 2 > > b > > 0 0 1 > > 0 0 0 > > b/a > > RANK ERROR > > b/a > > ^ ^ > > > > > > How to do this? > > > > > > Regards, > > Elias > > >
