Chuck,
Thanks for the reference. MCMC with "swapping" was my original goal and I
think I'll go with that in the long run--although using sample() has worked
out for now. I was initially concerned that checking all choose(n,2)
possible swaps would slow down the process, but in my case for choose(
On Fri, 29 Jan 2010, Andrew Rominger wrote:
Being reasonably sure that all valid permutations are equally probable is
important to me. I've played around with search algorithms in permuting
contingency tables and find that possible solutions decrease rapidly once
one starts assigning values, pa
Being reasonably sure that all valid permutations are equally probable is
important to me. I've played around with search algorithms in permuting
contingency tables and find that possible solutions decrease rapidly once
one starts assigning values, particularly if small values are assigned
first,
On Thu, 28 Jan 2010, Jason Smith wrote:
It wouldn't be guaranteed to produce any usable permutation, but it seems
like it would be much faster and so could be repeated until an acceptable
vector is found. What do you think?
Thanks--
Andy
I think I am not understanding what your ultimate goa
> It wouldn't be guaranteed to produce any usable permutation, but it seems
> like it would be much faster and so could be repeated until an acceptable
> vector is found. What do you think?
>
> Thanks--
> Andy
>
I think I am not understanding what your ultimate goal is so I'm not
sure I can give
Hi Jason,
Thanks for you suggestions, I think that's pretty close to what I'd need.
The only glitch is that I'd be working with a vector of ~30 elements, so
permutations(...) would take quite a long time. I only need one permutation
per vector (the whole routine will be within a loop that generat
I just realized I read through your email too quickly and my script does
not actually address the constraint on each permutation, sorry about that.
You should be able to use the permutations function to generate the vector
permutations however.
Jason
Andrew Rominger gmail.com> writes:
> I'm trying to permute a vector of positive integers > 0 with the constraint
Hi Andy
I'm not sure if you are explicitly wanting to use a sampling approach, but the
gtools library has a permutations function (found by ??permutation then ?
gtools::combinations
Hello,
I'm trying to permute a vector of positive integers > 0 with the constraint
that each element must be <= twice the element before it (i.e. for some
vector x, x[i] <= 2*x[i-1]), assuming the "0th" element is 1. Hence the
first element of the vector must always be 1 or 2 (by assuming the "0t
9 matches
Mail list logo
