I should add, that you should try replacing the leading 0 in 0 $ with
other digits, to get a better feel for the logic of these cases:
When you are working on the structure within the item, 1 $ gives you
the first element of the item, 2 $ gives you the unmodified item and 3
$ gives you a fatter item, and here's the 4 $ case:
(i.2 2),~ 4$0{i.6 2
0 1 0 1
0 1 0 0
2 3 0 0
(four numbers in your new item).
When you are working on the item itself, 1 $ gives you one copy of it,
2 $ gives you two copies of it, and 3 $ gives you three copies of it,
and here is how 4 $ works:
(i.2 2),~ 4$,:0{i.6 2
0 1
0 1
0 1
0 1
0 1
2 3
(four extra copies of your item)
This would be even clearer if instead of 0 { you had used 2 { ...
--
Raul
On Mon, Jan 14, 2013 at 7:24 AM, Raul Miller <rauldmil...@gmail.com> wrote:
> I do not see any use of take ({.) here, so I am a bit confused by your
> explanation.
>
> You do have 0 { i. 6 2 but that is not a 'take', that is a 'from'. If
> you want the result of 'from' to be items, you need to either make
> sure its left argument is rank 1 or you need to adjust the rank of the
> result. In this case, where your left argument to from is rank 0, you
> can use ,: to give your result the appropriate rank.
>
> In other words:
>
> (i.2 2),~ 0$0{i.6 2
>
> Here, 0 $ is removing the content of your item not the item itself
>
> (i.2 2),~ 0$,: 0{i.6 2
>
> Here, 0 $ is removing the item.
>
> (i.2 2),~ 0$(,0){i.6 2
>
> And, here, also, 0 $ is removing the item.
>
> --
> Raul
>
> On Mon, Jan 14, 2013 at 4:38 AM, Steven Taylor <tayl...@gmail.com> wrote:
>> thanks for the 0 0$0 comment idea.
>>
>> the bit that caught me was where an empty take comes back as 0 $ 0 from
>> take. The sequence was a little like this.
>>
>> (i.2 2),~ 0$0{i.6 2
>> 0 0
>> 0 1
>> 2 3
>>
>> Just trying to keep it as tacit as possible. i.e. 0$0 could be a list of
>> zero or more indices.
>>
>>
>> On 13 January 2013 21:23, Raul Miller <rauldmil...@gmail.com> wrote:
>>
>>> Note that (0 0$0), i. 2 2 would also work. The trailing dimension
>>> gets expanded, just like in your original case, so the net result is
>>> equivalent to (0 2$0,i. 2 2 which is to say nothing happens.
>>>
>>> But, depending on your situation, 0 0 $ 0 might be more generally
>>> useful than 0 2 $ 0.
>>>
>>> FYI,
>>>
>>> --
>>> Raul
>>>
>>> p.s. sorry about the hijacking
>>>
>>> On Sun, Jan 13, 2013 at 4:05 PM, Steven Taylor <tayl...@gmail.com> wrote:
>>> > I think the email thread got hijacked... but a follow up to the original
>>> > join question...
>>> >
>>> > Roger pointed out that I wasn't being logical (i.e. appending rank 1 to
>>> > rank 2 doesn't make sense).
>>> >
>>> > ... and if I do this, I now get back what I expected to see.
>>> >
>>> > (0 2$0), i.2 2
>>> > 0 1
>>> > 2 3
>>> >
>>> > So... I borrowed the idea of q's "reshape" and implemented it in J as a
>>> > helper verb. So far, it seems to be doing the trick.
>>> >
>>> > thanks for the comments and help.
>>> >
>>> >
>>> > On 13 January 2013 02:19, Raul Miller <rauldmil...@gmail.com> wrote:
>>> >
>>> >> On Sat, Jan 12, 2013 at 8:50 PM, Linda Alvord <lindaalv...@verizon.net>
>>> >> wrote:
>>> >> > As long as the ranks agree, u&v y -> u v y
>>> >> >
>>> >> > Would this be useful as a definition of compose?
>>> >>
>>> >> That is the definition for the monadic case but is incomplete since it
>>> >> does not mention the dyadic case.
>>> >>
>>> >> But note also that the dictionary's vocabulary is a reference work and
>>> >> it has already stated that the ranks must agree. Keep in mind that
>>> >> the dictionary also includes material such as
>>> >> http://www.jsoftware.com/help/dictionary/samp13.htm
>>> >>
>>> >> FYI,
>>> >>
>>> >> --
>>> >> Raul
>>> >> ----------------------------------------------------------------------
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>>> >>
>>> > ----------------------------------------------------------------------
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>>> ----------------------------------------------------------------------
>>> For information about J forums see http://www.jsoftware.com/forums.htm
>>>
>> ----------------------------------------------------------------------
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