[R] Subset sum problem.

Geert Janssens janssens-geert at telenet.be
Tue Dec 8 15:14:57 CET 2009


On Tuesday 8 December 2009, David Winsemius wrote:
> On Dec 8, 2009, at 8:29 AM, Geert Janssens wrote:
> > Thank you for your reply.
> >
> > Unfortunately, I don't have any experience with this kind of
> > mathematics. I
> > don't understand what the wiki page tries to tell me.
> >
> > Please don't misinterpret his, but I simply don't have the time to
> > learn a)
> > how to interpret the math description on wikipedia and b) how that
> > translates
> > into a new environment for me. I tried what I could, but just like all
> > volunteers on this list, my time is limited. I do have a practical
> > use for a
> > subset sum solving algorithm and R seems like a quite capable
> > package. But for
> > my novice eyes it looks I'll need to understand more of it than
> > entering a
> > simple formula which needs time I currently don't have.
>
> Dangerously close to:
>
> library(fortunes)
> fortune("brain surgery")
>
I understand. The problem in this case is easily described, but not easily 
solved. When I started to look for a solution, I didn't realize that.

> > That's why I asked if someone had solved it before, and was willing
> > to share
> > his/her program with me. I would be very grateful if someone can
> > help me here.
>
> An implementation was described in the last few months on this list.
>
I did find "The 'Subset matching' challenge" thread before asking any 
questions myself
(https://stat.ethz.ch/pipermail/r-help/2009-October/216604.html)

That's where I learned the "Subset sum" name in the first place, which I used 
to search further. The thread itself does not provide a solution in R, unless 
I'm really mistaking.

If you were thinking of another thread on the list, I sure could use a hint on 
what keywords to search for.

I also tried google in various incantations, but "R" is not really a useful 
search term in google... I find lots of theoretical descriptions of the subset 
sum problem, but no implementation in R.

Geert




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