Actually, 3 {.\ 1 2 3 4 5 worked:

{. 1 2 3 gives you 1
{. 2 3 4 gives you 2
{. 3 4 5 gives you 3

So... the result of using {. with a sliding window is the first
element from each of those window instances.

Thanks,

-- 
Raul



On Mon, Feb 19, 2018 at 3:24 PM, Skip Cave <s...@caveconsulting.com> wrote:
> Raul said:
>
> However, (1 2 3) is not a verb. So that gives you a domain error right
> there, regardless of any right argument:
>
> Doh! NOW i get it. ] is the verb and 3 is the noun.
>
> So any verb should work...
>
> 3<\1 2 3 4 5
>
> ┌─────┬─────┬─────┐
>
> │ 1 2 3 │ 2 3 4 │ 3 4 5 │
>
> └─────┴─────┴─────┘
>
>
> 3{.\1 2 3 4 5
>
> 1 2 3
>
> Hmmm..  why didn't that last one work?  Wait! I think I know...
>
> 3{."1\1 2 3 4 5
>
> 1 2 3
>
> Nope,
>
> 3{."0\1 2 3 4 5
>
> 1 2 3
>
> 2 3 4
>
> 3 4 5
>
> Yes! I'm not exactly sure why, but that's another way to achieve the same
> result that I was originally trying for.
>
> Skip
>
>
>
>
>
>
> Skip Cave
> Cave Consulting LLC
>
> On Mon, Feb 19, 2018 at 1:47 PM, Raul Miller <rauldmil...@gmail.com> wrote:
>
>> [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
>>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
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