[R] Convert timeseries to transition matrix

[Ingmar Visser]

Thanks to everyone for your quick and helpful answers!
ingmar


On 3/22/05 11:40 AM, "Christos Hatzis" <christos at nuverabio.com> wrote:

> Here is a way to do this:
> 
> x <- c(1,1,2,1,1,2,2,2,1,2)
> y <- cbind(x,c(x[-1],NA)) # time-shifted by one
> aggregate(y, by=list(y[,1],y[,2]), length)
> 
> -Christos Hatzis
> 
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Ingmar Visser
> Sent: Tuesday, March 22, 2005 11:21 AM
> To: R-help at stat.math.ethz.ch
> Subject: [R] Convert timeseries to transition matrix
> 
> Hi All,
> Does someone have an idea of how to cleverly convert a categorical
> timeseries into a transition matrix?
> Ie, I have something like:
> x<- c(1,1,2,1,1,2,2,2,1,2),
> And I want a matrix with counts and/or probabilities:
>> tr <- matrix(c(2,3,2,2),2,2)
>> tr
>      [,1] [,2]
> [1,]    2    2
> [2,]    3    2
> Meaning that there are two transitions from 1 to 1, two from 1 to 2, three
> from 2 to 1 and two from 2 to 2.
> Using for loops etc this is of course no problem, but I am curious whether
> there is a smarter solution.
> Any hints appreciated, Ingmar
> 
> --
> Ingmar Visser
> Department of Psychology, University of Amsterdam Roetersstraat 15, room
> 1009
> 1018 WB Amsterdam
> The Netherlands
> http://users.fmg.uva.nl/ivisser/
> tel: +31-20-5256735
> 
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> 

-- 
Ingmar Visser
Department of Psychology, University of Amsterdam
Roetersstraat 15, 1018 WB Amsterdam
The Netherlands
http://users.fmg.uva.nl/ivisser/
tel: +31-20-5256735