github.com/PuercoPop/advent-of-code/blob/… one question about using ⌿ to filter the 'rows' in a 2d matrix down to one. How do I extract the final row to a vector? ⊃ would get only the first element and ↑ would swap the axis but there would still be two. I used ∨⌿ as a work around but I'm guessing there is a more direct way?

@PuercoPop You can do a scan with right tack like so ⊢⌿. It starts with the first two rows and the accumulator is the second row, which ultimately picks the last row.

Sorry, that's reduce, not scan, but I think that's what you want.

@PuercoPop Actually, for this problem all you need just 1=≢⍵:,⍵⋄

since there would always be only one line left.

I already forget what I did for this problem though.

@LdBeth Ah makes sense, thanks.

@pitr I think dyalog<file.apl will do it.

didn't morten mention an ibeam for that in a presentation

Yes, 1010⌶ but it doesn't do that.

Maybe it should have such an option, though.

oh it displays the code

sorry should have checked

@PuercoPop Any first-axis reduction will do, or ⎕IO⌷ (you can replace ⎕IO with its value). But interestingly, I've been pondering a monadic function which would do exactly what you ask for, without resorting to strange things like reducing over a length 1 axis.