how to make the following boxed data from a list

Question

In J, I have a list like 1 2 3, I want to take *: and 2* to make it a box structure like

┌─┬─┐
│1│2│
│4│4│
│9│6│
└─┴─┘

or even

┌───┐
│1 2│
├───┤
│4 4│
├───┤
│9 6│
└───┘

How to do this? I would really appreciate your help.

Answer 1

You need to evoke a gerund in append mode (:0).

a =: 1 2 3
*:`+: (`:0) a
1 4 9
2 4 6

If you need them boxed, just ;/ them:

;/*:`+: (`:0) a
┌─────┬─────┐
│1 4 9│2 4 6│
└─────┴─────┘
;/ |:  *:`+: (`:0) a      NB. different axis
┌───┬───┬───┐
│1 2│4 4│9 6│
└───┴───┴───┘
 _3 <\6 1 $,*:`+: (`:0) a   NB. yet another axis
┌─┬─┐
│1│2│
│4│4│
│9│6│
└─┴─┘