Wow, thank you so much, friends, for so much help. With my present level of
profficiency in J, I'll need some time before I can make complete sense of
the J codes. Shall report back after that.
On 19 Feb 2018 01:10, "Cliff Reiter" <reit...@lafayette.edu> wrote:
> A cut variant of "words"
> (<;.1~1,2 ~:/\ ])I
>
> +-+----+---+---+-----+----+
>
> |a|bbbb|aaa|ccc|aaaaa|bbbb|
>
> +-+----+---+---+-----+----+
>
>
>
>
> On 2/18/2018 1:22 PM, David Lambert wrote:
>
>> While not answering your question, the verbs f f g and h solve the
>> problem. The first f uses complex copy to expand the input into same
>> letter groups then applies the correct substitutions to each group.
>>
>> group=: #~ (1 j. 0 ,~ 2 ~:/\ ])
>> words=: ;:@:group
>> substitute=: [: ; ('alpha'"_)`('beta'"_)`]@.('abc' i. {.)&.>
>>
>> f=: [: substitute words
>>
>> I=:'abbbbaaacccaaaaabbbb'[O=:'alphabetaalphacccalphabeta'
>> (O -: f) I
>> 1
>>
>>
>> Realizing I had overlooked `cut', words can also be written more directly
>> as
>>
>> words=: <;.2~ (1 ,~ 2 ~:/\ ])
>> (O -: f) I
>> 1
>>
>> We can mash it together
>> g=: [: ; (<@(('alpha'"_)`('beta'"_)`]@.('abc'i.{.));.2~ (1,~2~:/\]))
>> (O-:g) I
>> 1
>>
>>
>> Or use no boxes, but this idea depends on your actual application. Accept
>> the fill and remove it later.
>>
>> h=: ' ' -.~ [: , ((('alpha'"_)`('beta'"_)`]@.('abc'i.{.));.2~
>> (1,~2~:/\]))
>> (O-:h) I
>> 1
>>
>>
>> On 02/18/2018 07:00 AM, programming-requ...@forums.jsoftware.com wrote:
>>
>>> Date: Sun, 18 Feb 2018 14:08:45 +0530
>>> From: Arnab Chakraborty<arnab...@gmail.com>
>>> To:programm...@jsoftware.com
>>> Subject: [Jprogramming] sequential machine
>>> Message-ID:
>>> <CAM3RRn36JTQdtq_=cvhmwxycsgafjbmufmi4ougo00zuruz...@mail.gmail.com>
>>> Content-Type: text/plain; charset="UTF-8"
>>>
>>> Hello,
>>>
>>> I use state machines a lot in my programs (in other
>>> languages). I am trying to understand how I can use J for
>>> those purposes. I have read the Sequential Machines and
>>> Huffman Coding labs. But I am unable to see how to solve this
>>> toy problem (without using regexp):
>>>
>>> Input alphabet {a,b,c}
>>> I want to replace runs of 'a' with the word 'alpha', runs of 'b'
>>> with the word 'beta', and leave the 'c's unchanged.
>>>
>>> For example, abbbbaaacccaaaaabbbb becomes alphabetaalphacccalphabeta.
>>>
>>> The state diagram is like this, where the arcs are labelled as
>>> inp/out.
>>>
>>>
>>> [Cannot inline image]
>>>
>>> I have created the input map successfully (not sure if it is a
>>> good way, though):
>>>
>>> makemap =. 3 : '+/ (>:i.#y) *"0 1 a.="1 0 y'
>>> m=.makemap 'abc'
>>>
>>> I guess that this can be achieved using only outputs 0 and
>>> 2, since I am just interested in the runs.
>>>
>>>
>>> Also, since the output is not just a part of the input, f
>>> must be 2 or 3 or 4.
>>>
>>> But I am stuck at this point. If I use f=.2, then I can get
>>> a list of boundaries of all the runs. If I have to write another
>>> verb that will convert this list to the desired output, then
>>> basically I have to implement a simplified version of the same
>>> state machine inside that verb, which does not look good.
>>>
>>> f=.3 does not look promising either, since for 'c' I need to
>>> know the length of the run.
>>>
>>> How should I proceed?
>>>
>>>
>>> Thanks and regards,
>>>
>>> Arnab
>>>
>>
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