index =: $ #: [: I. , index ? 2 4$2
0 0 1 0 1 3 index ? 2 4 5$2 0 0 0 0 0 1 0 0 2 0 0 3 0 1 1 0 2 1 0 2 3 0 2 4 0 3 2 1 0 0 1 0 1 1 0 2 1 0 4 1 1 1 1 1 3 1 2 1 1 2 2 1 2 4 1 3 0 1 3 1 1 3 2 On Mon, Dec 11, 2023 at 11:06 AM LdBeth <andp...@foxmail.com> wrote: > I've been running to too many situations that I uses 4$.$.y a lot to > get indexes of all non zero elements to an array, I wonder if there > are any alternative ways to do that in J, especially when y is a > boolean array. > > Also monadic I. only works for 1D array, while ⍸ from APL works > for higher dimension cases, how to implement this in J? > > LdBeth > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
