This never seemed intuitive to me either. I think it means that the indices
are run together, i.e. in an ordinary table you have indices given by
{@:(i.&.>)@:$
like
┌───┬───┬───┬───┐
│0 0│0 1│0 2│0 3│
├───┼───┼───┼───┤
│1 0│1 1│1 2│1 3│
├───┼───┼───┼───┤
│2 0│2 1│2 2│2 3│
└───┴───┴───┴───┘
And when you "run together" the indices for two dimensions you get
([: ,&.>&>/ ({.~&.> <./@:(#@>))) @: (i.&.>) @: $
i.e. cut to the shorter of the lengths, then combine element by element,
like
┌───┬───┬───┐
│0 0│1 1│2 2│
└───┴───┴───┘Marshall On Sun, Jan 8, 2012 at 4:38 PM, Patrick van Beek <patvanb...@gmail.com>wrote: > Hi Alex, > > I never quite understood what *run together* means or why (<0 > 1)|: produces the diagonals. For me it was a case of experimenting with > the arguments and seeing what the result is rather than knowing if I > provide certain arguments I will get certain output - one of the few places > in the dictionary where the logic escapes me. > > Patrick > > On Sat, Jan 7, 2012 at 9:37 PM, Alex Giannakopoulos < > aeg...@blueyonder.co.uk > > wrote: > > > Yeah, great stuff that, Don, thanks. > > Could do with a fuller tutorial, though. > > Didn't find anything other than the 2 line description > > Might give it a go myself when I fully understand it. > > > > On 7 January 2012 13:28, Don Guinn <dongu...@gmail.com> wrote: > > > > > i.3 3 3 > > > 0 1 2 > > > 3 4 5 > > > 6 7 8 > > > > > > 9 10 11 > > > 12 13 14 > > > 15 16 17 > > > > > > 18 19 20 > > > 21 22 23 > > > 24 25 26 > > > (<0 1 2)|:i.3 3 3 > > > 0 13 26 > > > (<0 1)|:i.3 3 3 > > > 0 12 24 > > > 1 13 25 > > > 2 14 26 > > > > > > > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
