addendum, forget an extra ⍳≢
{(⍵⍴⍨≢⍵)⊂⍨(≢⍵)↑⍺/⍳≢⍵}
Cheers.
On Sat, Apr 11, 2020 at 9:19 PM Rowan Cannaday <cannad...@gmail.com> wrote:
> quick attempt:
>
> 3 {(⍵⍴⍨≢⍵)⊂⍨(≢⍵)↑⍺/⍵} 1 2 3 4 5 6 7
> ┏→━━━━━━━━━━━━━━━━━━┓
> ┃┏→━━━━┓ ┏→━━━━┓ ┏→┓┃
> ┃┃1 2 3┃ ┃4 5 6┃ ┃7┃┃
> ┃┗━━━━━┛ ┗━━━━━┛ ┗━┛┃
> ┗∊━━━━━━━━━━━━━━━━━━┛
>
>
> On Sat, Apr 11, 2020 at 9:02 PM Otto Diesenbacher-Reinmüller <
> ok...@diesenbacher.net> wrote:
>
>> Hi APLers!
>>
>> as I had a look into the archives, it seems ok, to post non bugs and
>> other topics not closely related to gnu-apl, but APL in general (for
>> sure, utilizing gnu-apl)? If my following post is offtopic please
>> excuse, and please let me know, where would be right place to discuss.
>>
>> So - i am quite new to APL, my road to APL? Some weeks ago, being a
>> hobbyist/partly professional Common Lisper, I stumpled upon April
>> (https://github.com/phantomics/april) and was fascinated by
>> APL. Always hungry for /something/ to get rid of Excel, I am starting
>> to explore the world of arrays ;).
>>
>> Having browsed through "Mastering Dyalog APL"(Legrand) and "APL_ The
>> Language and Its Usage"(Polivka/Pakin), to get some experience, I am
>> trying to solve (the easy parts) of the APL Dyalog Problem Solving
>> Competition (https://www.dyalog.com/student-competition.htm).
>>
>> I would like to share my experience, discuss the obstacles I
>> encounter, and especially get some advice/hints from you, the
>> experienced APLers! Perhaps this will lead to some blog-posts...
>>
>> Let's start with the first one:
>>
>> 1 chunk monkey
>> (
>> https://www.dyalog.com/uploads/files/student_competition/2019_problems_phase1.pdf
>> )
>>
>> "Write a function that, given a scalar or vector as the right argument
>> and a positive (>0)integer chunk size n as the left argument, breaks
>> the array's items up into chunks of sizen. If the number of elements
>> in the array is not evenly divisible by n, then the last chunkwill
>> have fewer than n elements. Hint: The partitioned enclose function ⊂
>> could be helpful for this problem."(from the exercise)
>>
>> hmmm, as in the exercise stated, dyadic ⊂ (partition) is to be used.
>> So the real challenge is to generate the correct vector as left
>> argument for ⊂, right?
>>
>>
>> ⍝ first try:
>> ∇ z← size chunkmonkey1 a
>> z←((⍴a)↑(size/⍳⍴a)) ⊂ a
>> ∇
>> ⍝ BUT
>> ⍝ - doesn't work with a scalar as asked
>> ⍝ - ((⍴a)↑(size/⍳⍴a)) seems inefficient, as we make a to big
>> ⍝ vector and cut it down afterwards... Is this a common/fine
>> ⍝ pattern?
>>
>>
>> ⍝ second try:
>> ∇ z← size chunkmonkey2 a
>> →((0=≢⍴a)∧1=≢a)/skalar ⍝ matches a skalar, but not ''
>> z←((≢a)↑(size/⍳≢a))⊂a ⍝ ≢ or ⍴ in this case?
>> →0
>> skalar:
>> z←a
>> ∇
>>
>> ⍝ correct, but feels clumsy...
>> ⍝ - ≢ seems more acurately than ⍴ in this case?
>> ⍝ - should be doable without jump?
>> ⍝ - still the inefficient vector
>>
>> Final thoughts for now:
>>
>> What I learned/understood with this exercise: / is not only reduce
>> (operator), but also dyadic functions filter and especially expand
>> (not all APL-variants?).
>>
>> Checking for types is not easy. 0=⍴N is a scalar. Howto check for a
>> string?
>>
>> br & and many thanks for any hints, Otto
>>
>> --
>> Dipl. Ing. (FH) Otto Diesenbacher-Reinmüller
>> diesenbacher.net
>> Salzburg, Österreich
>>
>>
