[R] how to permute, simulate Markov chain

David Winsemius dwinsemius at comcast.net
Sun Nov 15 23:10:39 CET 2009


On Nov 15, 2009, at 4:11 PM, martin08 wrote:

>
> Hi all,
>
> I am new to R. Can someone please give me some hints in how to do the
> following things:
>
> 1- Get ONE permutation of a set. I have looked at the gregmisc  
> package's
> permutations() method, but I just want to get one permutation at a  
> time.

Assuming that set1 is your set object  and x is <= number of  
permutations of z things from set1, then

permutations(set1, z)[x] will give your the x-th permutation.

the "[" operator/function can often be appended to the end of a  
function to extract the desired subset.

>
> 2- Simulate a Markov chain in R. For instance, I want to simulate  
> the simple
> random walk problem, in which a person can walk randomly around 4  
> places. I
> know how to set up the transition matrix in R. I'm stuck at what to  
> do next.

Learn to search for yourself:

http://search.r-project.org/cgi-bin/namazu.cgi?query=%22transition+matrix%22+markov&max=100&result=normal&sort=score&idxname=Rhelp08&idxname=Rhelp02

>
> I'm grateful if someone can give me hint or a pointer.
>
> Thanks.
>
> Martin
> -- 
> View this message in context: http://old.nabble.com/how-to-permute%2C-simulate-Markov-chain-tp26363411p26363411.html
> Sent from the R help mailing list archive at Nabble.com.
>
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> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
Heritage Laboratories
West Hartford, CT




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