Hi Chris, Well there is information on the vocabulary page for Table http://www.jsoftware.com/help/dictionary/d420.htm
also Nuvoc has good information on this verb http://www.jsoftware.com/jwiki/Vocabulary/slash#dyadic The actual shape of a box is empty since the box is an atom. In the case of 1 2 +/ i. 4 the shape is actually 2 4 i.e. 2 rows of 4 not 2 1 < 1 2 +/ i. 4 ┌───────┐ │1 2 3 4│ │2 3 4 5│ └───────┘ $ < 1 2 +/ i. 4 $ each < 1 2 +/ i. 4 ┌───┐ │2 4│ └───┘ If you wanted the two rows to be in their own boxes then you could do ;/ 1 2 +/ i. 4 ┌───────┬───────┐ │1 2 3 4│2 3 4 5│ └───────┴───────┘ or <"1 [ 1 2 +/ i. 4 ┌───────┬───────┐ │1 2 3 4│2 3 4 5│ └───────┴───────┘ $ <"1 [ 1 2 +/ i. 4 2 The above shows that the shape of the two boxes is not actually 1 2 because each box is an atom the shape is actually just 2. You are correct that an understanding of rank and shape is key to getting J to work for you. If you are looking for information I have always found Henry Rich's J for C Programmers much more accessible than the J dictionary. Chapters 5 and 6 are really good at explaining rank and shape with regard to verbs. http://www.jsoftware.com/help/jforc/contents.htm Also, look at Nuvoc on the wiki. This is a crowd sourced resource organized by Ian Clark and Henry Rich which many have found useful. http://www.jsoftware.com/jwiki/NuVoc Enjoy the ride as you learn J. Welcome aboard. Cheers, bob On Sep 24, 2014, at 10:35 PM, Chris Wright <[email protected]> wrote: > Hi > > Could I work out from the docs that > > < 1 2 +/ i. 4 > > ┌───────┐ > > │1 2 3 4│ > > │2 3 4 5│ > > └───────┘ > > will give the above (2 1) shape result > > > and not a (1 2) result like below? > > > ┌───────┬───────┐ > > │1 2 3 4│2 3 4 5│ > > └───────┴───────┘ > > > > > With the (2,1) it's obvious that two 1-cells are returned, and with (1,2) > it's not obvious (where is the boundary b/n them), but I wonder if I could > have worked out the shape of the output from the docs alone? > > > with thanks > > > Chris > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
