[Jprogramming] Re: Coding Problem

[June Kim]

One more solution:

cs=: [: <. [ %~ [: # ]
b1=: 0 = cs | ]
b2=: ] < [ * cs
f=: (b1*.b2) < ;. 1 ]


2006/11/15, June Kim <juneaftn at gmail.com>:
> 2006/11/15, June Kim <juneaftn at gmail.com>:
> > from http://c2.com/cgi/wiki?CodingProblem
> >
> > Given K, answer an ordered collection of K ordered collections of size
> > approximately N / K, such that the first contains the first N / K
> > objects, the second the second N / K, etc.
> >
> > There is a J solution on that page but it doesn't work in all cases.
> >
> > Following is my solution (with one issue though):
> > c=: [: <. [ %~ [: # ]
> > hd=: ([: <: [) * c
> >
> > b1=: hd {.]
> > b2=: hd }.]
> > f=: <@b2 ,~  - at c <\ b1
> >
> > assert (0 1 2;3 4 5;6 7 8)-:3 f i.9
> > assert ((,:0);1 2)-:2 f i.3
> > assert (0 1 2;3 4 5;6 7 8 9)-:3 f i.10
> >
> > assert ((0$<''),<0 1)-: 1 f i.2      NB.  $ > 1 f i.2  is 1 2, not 2
> > as I expected
> >
> > I don't like the last line -- that problem occurs once in a while. How
> > could I make it to pass  "assert (<0 1)-:1 f i.2" with a simple
> > modification?
>
> In other words, assert (,:<0 1)-: 1 f i.2
>
> Hm... Maybe I was wrong.
>
> My solution's result is more consistent than how I wanted the result to be.
>
> The return value of f is, an array of rank 1. Each item of the array
> is of rank 1. Then my previous solution is more consistent.
>
> I am sometimes confused(and make mistakes) with the fact that in J we
> have scalars of which rank is empty, which is different from a rank-1
> array of a single item. Even a boxed value can a scalar or a rank-1
> array(say <1 and ,:<1).
>
> >
> > I am interested in seeing other J solutions.
> >
>
> Still.
>