Thank you Bill. That was just what I needed to understand (".) better,
in the spirit of what I was trying to do.Thank you also, Raul, Roger and Devon. These furnish me with counterparts to techniques familiar to me in APL+Win. I shall have a use for all of them in my current project. Ian On Tue, Apr 6, 2010 at 10:50 AM, bill lam <[email protected]> wrote: > For your particular case, since ". is rank-1, it is sufficient to coerce > result from it to rank-1 so that the assembled will be rank-2. > > ,@". ":i.3 1 > 0 > 1 > 2 > > ,@". ":i.3 2 > 0 1 > 2 3 > 4 5 > > mar, 06 Apr 2010, Ian Clark skribis: >> I was afraid that would be the answer. >> >> The inconvenience to my code is negligible. It just needs one more >> line, with an (if.) in it. What distresses me is my failure to >> understand why it happens. It makes me suspicious of my whole >> data-storage approach. >> >> I need to store a 2-D integer array, call it z, in an ascii text file >> and recover it on reloading the file. >> Suppose 'a b'=:$z >> Proviso: z is one of several arrays of mixed data. I want to retain a >> visual check on the file contents that they all match-up by rows >> (numbered: i.a). Without this proviso, a sensible thing to do is to >> store the contents of z as a vector and reconstruct it from a >> knowledge of the number of rows, (a). >> Taking a simple minded approach, however, I can use (":) to stuff z in >> a file, and (".) to recover it again from the (2-D) file image. This >> seems adequate and reliable provided a>1 and b>1. I just wouldn't have >> anticipated it breaking down for b=1, which is not an uncommon case to >> arise. >> >> Clearly this is not the approach an experienced J-er would take, and >> I'd like to know what that is. >> >> I don't want to drag this thread off-topic. It just seemed related in >> my mind to the problem of predicting the number of display-lines in z >> -- or do I mean (":z)? Or (". ":z)? >> >> Ian >> >> >> On Tue, Apr 6, 2010 at 12:29 AM, Roger Hui <[email protected]> wrote: >> [---=| TOFU protection by t-prot: 55 lines snipped |=---] > > -- > regards, > ==================================================== > GPG key 1024D/4434BAB3 2008-08-24 > gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3 > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
