That's an interesting question. Here's an intermediate result:
sdata i."1(1) 1 │ 2 2 │ 1 3 │ 1 4 │ 0 For that matter: sdata 1 2 │ 1 2 1 │ 1 3 1 │ 1 3 2 │ 1 4 0 │ 1 In other words, since the array is sparse, the first row does not really "exist" - it's just the default value. In other words, you'd be getting a dense result rather than a sparse result, to have the "this value does not show up" behavior from i. work for you here. Sparse matrices are quirky and limited (and, perhaps, a bit "lazy").. -- Raul On Fri, Sep 26, 2014 at 8:30 AM, Ben Gorte - CITG <[email protected]> wrote: > Good afternoon, > > I was finding a bug in my program that finally boiled down to this: > > ]data =: #: i.5 NB. some test data > 0 0 0 > 0 0 1 > 0 1 0 > 0 1 1 > 1 0 0 > sdata =: $.data NB. now sparse > > data i."1 (1) > 3 2 1 1 0 > > 0$. sdata i."1 (1) > 0 2 1 1 0 > > Shouldn't these be the same? > > Thanks for any advice, > > Ben > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
