[M=:1 _1 0 1,1 1 _1 1,:0 1 0 _1
1 _1 0 1
1 1 _1 1
0 1 0 _1
0([EMAIL PROTECTED] <@#: I.@,@:=) M
+---+---+---+
|0 2|2 0|2 2|
+---+---+---+
NB. coordinates of zeroes
(<1 _1)(0([EMAIL PROTECTED] <@#: I.@,@:=) M)}<"0 M
+----+--+----+--+
|1 |_1|1 _1|1 |
+----+--+----+--+
|1 |1 |_1 |1 |
+----+--+----+--+
|1 _1|1 |1 _1|_1|
+----+--+----+--+
NB. replace boxed zeroes by 1 _1
<@{"1 (<1 _1)(0([EMAIL PROTECTED] <@#: I.@,@:=) M)}<"0 M
+--------------------+----------+----------------------+
|+--------+---------+|+--------+|+---------+----------+|
||1 _1 1 1|1 _1 _1 1|||1 1 _1 1|||1 1 1 _1 |1 1 _1 _1 ||
|+--------+---------+|+--------+|+---------+----------+|
| | ||_1 1 1 _1|_1 1 _1 _1||
| | |+---------+----------+|
+--------------------+----------+----------------------+
NB. use catalogue to make all combinations
>,;<@{"1 (<1 _1)(0([EMAIL PROTECTED] <@#: I.@,@:=) M)}<"0 M
1 _1 1 1
1 _1 _1 1
1 1 _1 1
1 1 _1 1
1 1 1 _1
1 1 _1 _1
_1 1 1 _1
_1 1 _1 _1
replaceZeroes M
1 _1 _1 1 1 _1 1 1 1 1 _1 1 _1 1 _1 _1 _1 1 1 _1 1 1 _1 _1 1 1 1 _1
R.E. Boss
> -----Oorspronkelijk bericht-----
> Van: [EMAIL PROTECTED] [mailto:programming-
> [EMAIL PROTECTED] Namens Geoff Canyon
> Verzonden: zondag 9 maart 2008 21:59
> Aan: Programming forum
> Onderwerp: Re: [Jprogramming] Turning 0 into _1 1 in a list
>
> I think the eventual solution I came up with was somewhat similar to
> this. Here's my solution:
>
> replaceZeroes =: (;@:;@:(_4([:<(((_1 1 (] i.&0)}"0 1 ])`])@.(# =
> i.&0)))\]))^:_
>
> I spent some time trying to figure out how to apply the replacement
> repeatedly before boxing and then unbox at the end, to minimize boxing/
> unboxing, but I couldn't get that to work. So in the above, the boxing/
> unboxing happens for each replacement. This isn't so bad in my
> particular case since no list has more than three zeroes in it. If the
> lists had many zeroes, the whole thing would come apart, since I'm
> starting with 512 lists of 27 elements, so a bunch of zeroes would
> quickly result in millions of lists. As it is, I end up with less than
> a thousand.
>
> Still I wonder that there seems to be no way to avoid boxing/unboxing?
> If I have a list and I want to transform that list, with the subsets I
> take potentially changing in length, I can't do that without boxes?
>
> Say I have a list like this: 1 2 3 4 5 6 7 8
>
> And I want the result to be a list that a duplicate for each prime in
> the list:
>
> 1 2 2 3 3 4 5 5 6 7 7 8
>
> Are boxes the only/best way?
>
> regards,
>
> Geoff
>
> On Mar 4, 2008, at 5:17 AM, Raul Miller wrote:
>
> > I have some comments in addition to R.E.Boss's comments
> > (and using his M)
> > M=:1 _1 0 1,1 1 _1 1,:0 1 0 _1
> >
> > A simple approach to supressing fill uses box (<) followed
> > by raze (;). In other words:
> >
> > <@(_1 1 (] i.&0)}"0 1 ])`<@.(# = i.&0)"1 M
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