Great! While we are at it, the next question could be how to go the other way around and create a matrix from indices and values?
s =: $.d=: (?. 3 4$2) * ?. 3 4$100 i =: 4$.s v =: 5$.s we can use "scatter amend" since J version 9: v i } 3 4$0 to create a dense matrix, but not v i } 1$.3 4;0 1;0 NB. amend an 'empty' sparse matrix |index error | v i}1$.3 4;0 1;0 to create a sparse one. Is this a bug/not yet implemented? Good old: v (;/i) } 1$.3 4;0 1;0 NB. with boxed indices still works. greetings Ben On Mon, 20 Jan 2020 at 16:31, 'Sergey Kamenev' via Programming < [email protected]> wrote: > 20.01.2020 7:57, Ben Gorte: > > Do you mean 4$.s ? > > Thanks. That's what I need. > > Sergey > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
