"[1]More generally, >x may be a list whose successive elements are
(possibly) boxed arrays that specify selection along successive axes of y ."
(2 0;1 3) { i. 5 5
10 8
Here, 2 selects along the first axis of y and 0 selects along the second
axis of y. Independently, 1 selects along the first axis of y and 3 selects
along the second axis of y.
A possibly confusing issue is that the definition is specified assuming
issues of rank have already been dealt with. In this case the rank for x
is 0. So each box is treated independently.
It's important to remember that the dictionary is a reference work, not a
tutorial or introductory work.
Does this help?
Thanks,
--
Raul
On Mon, Mar 17, 2014 at 12:21 AM, June Kim (김창준) <[email protected]> wrote:
> Hi
>
> I thought the J dictionary is comprehensive. However, I think the
> definition for From isn't. See
> http://jsoftware.com/help/dictionary/d520.htm
>
> <quote>
> [0]If x is an integer in the range from -n=: #y to n-1 , then x{y selects
> item n|x from y .
>
> ......
>
> [1]More generally, >x may be a list whose successive elements are
> (possibly) boxed arrays that specify selection along successive axes of y .
>
> [2]Finally, if any r=:>j{>x used in the selection is itself boxed,
> selection is made by the indices along that axis that do not occur in >r .
>
> [3]Note that the result in the very last dyadic example, that is, (<<<_1){m
> , is all except the last item.
> </quote>
>
> [0] is the case when x is an integer.
> [1] is the case for (<2 0;1 3){t.
> [2] is the case for (<<<1){t.
>
> Where is the description for the case of (2 0;1 3){t in the definition
> above? I inferenced its meaning from running and reading other texts(like J
> for C).
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