[I'm using parenthesis, here to separate j expressions from
surrounding english text. That might be a little unfamiliar, but
hopefully it's not too bad... And, on the plus side, parenthesis are
valid J when their contents are valid J.]

] does replicate the right argument. And, for monadic verbs - which is
what we get for (x verb\ y) contexts - the right argument is the only
argument.

But keep in mind that the verb (]\) has two definitions: a monadic
definition and a dyadic definition. So you should expect a different
result from (3 ]\ i.4) than what you get from (]\ i.4)

And, this might be throwing you off: both (x verb\ y) and (verb\ y)
use the monadic definition of (\)'s verb argument.

However, (1 2 3) is not a verb. So that gives you a domain error right
there, regardless of any right argument:

   1 2 3\
|domain error

To see what ] is doing, though, maybe it's better to replace it with <

For example, try:   3 <\ i.6

Thanks,

-- 
Raul



On Mon, Feb 19, 2018 at 2:38 PM, Skip Cave <s...@caveconsulting.com> wrote:
> Thanks to all the informative responses. I knew there had to be a way to
> use \ for the sliding window, but
> it didn't occur to me to use ] to access the right argument.
>
> so
>
> ]\1 2 3
>
> 1 0 0
>
> 1 2 0
>
> 1 2 3
>
> but
>
> 1 2 3\1 2 3
>
> |domain error
>
> | 1 2 3 \1 2 3
>
> I thought that  ] replicated the right argument, but appaently not.
>
> Why does the first example work, and the second doesn't?
> What exactly is the ] doing in the first example?
>
> Skip
>
>
> Skip Cave
> Cave Consulting LLC
>
> On Mon, Feb 19, 2018 at 1:09 PM, Skip Cave <s...@caveconsulting.com> wrote:
>
>> How can one create a sliding window in J?
>>
>> 3 sw i.6
>>
>> 0 1 2
>> 1 2 3
>> 2 3 4
>> 3 4 5
>>
>> 4 sw i.7
>> 0 1 2 3
>> 1 2 3 4
>> 2 3 4 5
>> 3 4 5 6
>> 4 5 6 7
>>
>> What is the J code for sw?
>>
>>
>>
>>
>>
>> Skip Cave
>> Cave Consulting LLC
>>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm

Reply via email to