You could do it this way:
itt=. 1e5 6?@$0 NB. Generate 6 columns of numbers between 0 and 1
NB. Multiply by scaling factor to force sum to 172, then round and
NB. select those that sum to 172 after rounding.
itt=. itt#~172=+/"1 ([: <. 0.5 + ] * 172 % +/"1)"1 ] itt
3{.itt=. <.0.5+itt*("1 0)172%+/"1 itt
30 62 7 22 50 1
35 32 24 34 27 20
21 39 1 14 43 54
NB. Remove any row with element not less than or equal to 70:
$itt=. itt#~*./"1 itt<:70
52205 6
So, over half of our random selections can be made to work.
On Wed, Jun 27, 2018 at 2:24 AM, Skip Cave <s...@caveconsulting.com> wrote:
> Raul, Robert, Jimmy, Louis, Bo, Rob,
> Thanks so much for all the thoughtful and interesing answers. Your examples
> gave me much insight on how the while. do. control structures work, which I
> can never seem to remember. I also got a better understanding of
> itemize/laminate, very useful for sticking vectors together.
>
> In my particular case. I didn't have to generate millions of combinations,
> so efficiency wasn't much of an issue for me.
>
> Skip
>
>
> On Tue, Jun 26, 2018 at 9:12 AM Skip Cave <s...@caveconsulting.com> wrote:
>
> > I want to generate n sets of 6 random integers from 1->70 where each set
> > of 6 integers sums to 172
> >
> > Here's my first try:
> >
> > ts =: 3 : 0
> >
> > b=: 2 6$0
> >
> > for. i.y do. a=:1+6?70
> >
> > b=:b,a
> >
> > end.
> >
> > b#~172=+/"1 b
> >
> > )
> >
> > Test it:
> >
> > ts 1000
> >
> > 27 60 5 24 53 3
> >
> > 38 35 3 15 57 24
> >
> > 16 29 19 50 4 54
> >
> > This generates some 6-element vectors that sum to 172 by elimination, but
> > I don't have control of how many vectors it produces.
> >
> >
> > I want to change the logic in the loop so that it keeps generating sets
> of
> > 6 random integers, testing whether they sum to 172, saving just the sets
> > that sum to 172, until I have saved y random sets that sum to 172, and
> then
> > exits.
> >
> >
> > Any help would be appreciated.
> >
> >
> > Skip
> >
> >
> > Skip Cave
> > Cave Consulting LLC
> >
> ----------------------------------------------------------------------
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>
--
Devon McCormick, CFA
Quantitative Consultant
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