No worries, also FYI I tend to use more ( ) than necessary to clarify very
train groupings, but @ in this example operates with a higher level operator
precedence, so the innermost parens are not required (sorry, should have
removed them).
Dissect would also show this quite clearly.
2 3 (<@<@<@[{]) 1 2 3 4 5
1 2 5
ex=:<@<@<@[ { ]
2 3 ex 1 2 3 4 5
1 2 5
Best, Rob
> On 8 Nov. 2016, at 6:27 pm, Skip Cave <[email protected]> wrote:
>
> Rob,
>
> Thanks. 'Except' is a very useful tool to keep in my toolbox. Frankly, I
> think there needs to be a wiki page on the J Software site dedicated to
> exploring this option in more depth. I would have never found out about
> this if Raul hadn't pointed it out
>
> The idea is touched on briefly in the page Raul pointed out
> <http://www.jsoftware.com/help/dictionary/d520.htm>, and also hinted at
> briefly on the 'from' vocabulary page
> <http://code.jsoftware.com/wiki/Vocabulary/curlylf>, but I think the
> subject needs much more explanation. A search for 'except' on the J
> software site should lead one to a page full of examples as the top search
> result. The examples should start very simply, and gradually show more &
> more complex options.
>
> Skip
>
> Skip Cave
> Cave Consulting LLC
>
> On Tue, Nov 8, 2016 at 2:08 AM, Rob Hodgkinson <[email protected]> wrote:
>
>> Hi Skip,
>>
>> 2 3 ((<@<@<@[){]) 1 2 3 4 5
>> 1 2 5
>>
>> ex=:(<@<@<@[){]
>> 2 3 ex 1 2 3 4 5
>> 1 2 5
>>
>> Rob
>>
>>
>>> On 8 Nov. 2016, at 5:44 pm, Skip Cave <[email protected]> wrote:
>>>
>>> Aha! except! I had no idea that from '{' had such a useful option.
>>>
>>> (<<< 1 4 5 7) { 2 3 5 7 11 14 56 78 95
>>>
>>> 2 5 7 56 95 NB. Cool!
>>>
>>>
>>>
>>> If i wanted to make a dyadic verb 'ex' that worked just like the above,
>> how
>>> could I do that?
>>>
>>>
>>> 1 4 5 7 ex 2 3 5 7 11 14 56 78 95
>>>
>>> 2 5 7 56 95
>>>
>>>
>>>
>>> ex =: [:@<@<@<[{]
>>>
>>> 2 3 ex 1 2 3 4 5
>>>
>>> |index error: ex
>>>
>>> | 2 3 ex 1 2 3 4 5
>>>
>>>
>>> Nope! that didn't work.
>>>
>>>
>>> Skip
>>>
>>> Skip Cave
>>> Cave Consulting LLC
>>>
>>> On Tue, Nov 8, 2016 at 12:32 AM, Raul Miller <[email protected]>
>> wrote:
>>>
>>>> 2 { 2 3 5 7 11
>>>> 5
>>>> (<<<2) { 2 3 5 7 11
>>>> 2 3 7 11
>>>>
>>>> Look for the word "except" at http://www.jsoftware.com/help/
>>>> dictionary/d520.htm
>>>>
>>>> Thanks,
>>>>
>>>> --
>>>> Raul
>>>>
>>>>
>>>> On Tue, Nov 8, 2016 at 12:17 AM, Skip Cave <[email protected]>
>>>> wrote:
>>>>> Nice! Xiao-Yong's verb does exactly what I need.
>>>>>
>>>>> f=:(] +:@{`[`]} <@<@<@]{[)"_ 0 [:I.2=/\]
>>>>>
>>>>> t =. 1 2 2 4 1 5 3 4 4 4 2 3 3
>>>>>
>>>>> f t
>>>>>
>>>>> 1 4 4 1 5 3 4 4 4 2 3 3
>>>>>
>>>>> 1 2 2 4 1 5 3 8 4 2 3 3
>>>>>
>>>>> 1 2 2 4 1 5 3 4 8 2 3 3
>>>>>
>>>>> 1 2 2 4 1 5 3 4 4 4 2 6
>>>>>
>>>>>
>>>>> I can understand [:I.2=/\]. Using I. is the perfect way to find the
>>>>> indices of the dups. However, the rest of that big infinite-rank tacit
>>>>> expression to the left must generate each of the reduced items. I'm
>>>> totally
>>>>> lost trying to figure that out. Why the zero? Why three <@? I thought [
>>>>> represented a left argument, but there isn't a left argument. Any help
>> is
>>>>> appreciated.
>>>>>
>>>>>
>>>>> Skip
>>>>>
>>>>> Skip Cave
>>>>> Cave Consulting LLC
>>>>>
>>>>> On Mon, Nov 7, 2016 at 10:25 PM, Xiao-Yong Jin <[email protected]>
>>>>> wrote:
>>>>>
>>>>>> So you probably just need this:
>>>>>> f=:(] +:@{`[`]} <@<@<@]{[)"_ 0 [:I.2=/\]
>>>>>> or really the adverb
>>>>>> a=:1 :'u@(] +:@{`[`]} <@<@<@]{[)"_ 0 [:I.2=/\]'
>>>>>>
>>>>>> You may find different solutions if you abstract your problem
>>>> differently.
>>>>>>
>>>>>>> On Nov 7, 2016, at 9:30 PM, Skip Cave <[email protected]>
>>>> wrote:
>>>>>>>
>>>>>>> Very interesting. Quite a difference in space and time usage, not to
>>>>>>> mention length of the tacit code.
>>>>>>>
>>>>>>> For my application, a rank 0 or 1 in the summed result isn't all that
>>>>>>> critical. As long as the contents of each box can be used in further
>>>>>>> arithmetic and Boolean operations (e.g. it's not text), then I'm ok.
>>>>>>>
>>>>>>>
>>>>>>> It looks like nouns with ranks 0 or 1 don't affect the outcome of
>>>> simple
>>>>>>> arithmetic operations:
>>>>>>>
>>>>>>>
>>>>>>> ($4);($,4);(4=,4);(1+4);(1+,4);((1+4)=1+,4);($1+4);($1+,4)
>>>>>>>
>>>>>>> ┌┬─┬─┬─┬─┬─┬┬─┐
>>>>>>>
>>>>>>> ││1│1│5│5│1││1│
>>>>>>>
>>>>>>> └┴─┴─┴─┴─┴─┴┴─┘
>>>>>>>
>>>>>>> The only time the difference becomes an issue:
>>>>>>>
>>>>>>> ($4)=($,4)
>>>>>>>
>>>>>>> |length error
>>>>>>>
>>>>>>> | ($4) =($,4)
>>>>>>> But I don't care about this.
>>>>>>>
>>>>>>> Actually, Mike Day spotted what I was really trying to attempt.
>>>>>>> The original starting vector is:
>>>>>>>
>>>>>>> n =: 1 2 2 4 1 5 3 4 4 4 2 3 3
>>>>>>>
>>>>>>> Then I box at each possible pair of integers using an infix
>>>>>> sliding-window
>>>>>>> on each pair of integers. This sliding box scheme was just to
>> identify
>>>>>> all
>>>>>>> the duped pairs in the original vector.
>>>>>>>
>>>>>>> ]N =: 2<\pp
>>>>>>>
>>>>>>> ┌───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┐
>>>>>>>
>>>>>>> │1 2│2 2│2 4│4 1│1 5│5 3│3 4│4 4│4 4│4 2│2 3│3 3│
>>>>>>>
>>>>>>> └───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┘
>>>>>>>
>>>>>>>
>>>>>>> What I ultimately wanted is a verb that will replace the duped pairs
>>>> in
>>>>>> the
>>>>>>> *original* un-boxed vector, one at a time:
>>>>>>>
>>>>>>> n =: 1 2 2 4 1 5 3 4 4 4 2 3 3
>>>>>>>
>>>>>>> f n
>>>>>>>
>>>>>>> 1 4 4 1 5 3 4 4 4 2 3 3
>>>>>>>
>>>>>>> 1 2 2 4 1 5 3 8 4 2 3 3
>>>>>>>
>>>>>>> 1 2 2 4 1 5 3 4 8 2 3 3
>>>>>>>
>>>>>>> 1 2 2 4 1 5 3 4 4 4 2 6
>>>>>>>
>>>>>>> Of course, the final row lengths will be one shorter that the
>> original
>>>>>> row
>>>>>>> length.
>>>>>>>
>>>>>>> Skip
>>>>>>> ------------------------------------------------------------
>>>> ----------
>>>>>>> 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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