Why do I think "table" is [so appropriately] the dyad of u/ (whose monad is insert)? They both represent fundamental rank changing operations, one (contraction) whereby a dimension is absorbed and the rank is reduced by one, the other (cartesian product) whereby dimensions are concatenated and ranks are summed. OK, not such a blinding insight, but these types of rank changing operation (including ,. ,:) are what makes array manipulation useful.
All benefits from array manipulation come *only* when there is a change in rank. Does this make sense? Regards Graham ----- Original Message ----- > Date: Wed, 24 Feb 2010 07:30:10 -0800 > From: Roger Hui <[email protected]> > Subject: Re: [Jprogramming] Agreement > To: Programming forum <[email protected]> > Message-ID: <[email protected]> > Content-Type: text/plain; charset=iso-8859-1 > > Now you've got me curious. Why do you think "table" > is the dyad of u/ (whose monad is insert)? > > (There is no right or wrong answer.) > > > > ----- Original Message ----- > From: Graham Parkhouse <[email protected]> > Date: Wednesday, February 24, 2010 5:04 > Subject: Re: [Jprogramming] Agreement > To: [email protected] > > > Thank you, Roger! I'm very happy with that. I have *just* > > understood why > > table is the dyadic equivalent of insert. That's brilliant! Till > > now, I had > > just seen it as two useful verbs using the same symbols. > > > > Regards > > > > Graham > > > > > > > > ?----- Original Message ----- > > > > > > Message: 6 > > > Date: Tue, 23 Feb 2010 10:11:02 -0800 > > > From: Roger Hui <[email protected]> > > > Subject: Re: [Jprogramming] Agreement > > > To: Programming forum <[email protected]> > > > Message-ID: <[email protected]> > > > Content-Type: text/plain; charset=iso-8859-1 > > > > > > If v has ranks 0, x v"0 _ y or x v/y should have shape ($x),($y),s > > > where s is the maximal shape of the individual results. > > > If v always returns a rank 0 result than that simplifies > > > to ($x),$y . > > > > > > > > > > > > ----- Original Message ----- > > > From: Graham Parkhouse <[email protected]> > > > Date: Tuesday, February 23, 2010 10:04 > > > Subject: [Jprogramming] Agreement > > > To: [email protected] > > > > > > > I have a problem which is basically > > > > > > > >????? x v y > > > > > > > > x contains one sort of data and y a completely different > > sort. For > > > > simplicity let's say v has rank 0 and returns a rank 0 > > result. I > > > > would like > > > > the result to have shape ($x),$y irrespective of the values of > > > > $x and $y, > > > > but I cannot (easily) unless one is a prefix of the other. > > > > > > > > Why was this rule introduced? > > > > > > > > In my particular problem part of $y is pervasive through the > > > > process and I'm > > > > introducing additional structure through x. > > > > > > > > Regards > > > > > > > > Graham > > > > ----------------------------------------------------------------- > > ----- > > For information about J forums see > http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
