[R] Simulation in R

[Petr Pikal]

Hi

On 7 Dec 2006 at 1:20, Alexander Geisler wrote:

Date sent:      	Thu, 07 Dec 2006 01:20:49 +0100
From:           	Alexander Geisler <alexander.geisler at gmail.com>
To:             	r-help at stat.math.ethz.ch
Subject:        	[R] Simulation in R

> Hello!
> 
> I have the following problem.
> 
> My code:
> 
> --snip--
> 
> ergebnisse <- rep(0, each=2)
> stichproben <- rep(0, each=2)
> 
> for (i in seq(1:2)) {
> n <- dim(daten)[1]  	
> ix <- sample(n,200) 	# producing samples
> samp_i <- daten[ix,]  	
> stichproben[i] <- samp_i     # doesn’t works

If I understand your code correctly, you could use list.

stichproben <-vector("list",2)
and
stichproben[[i]] <- samp_i

> 
> # Calculation of the model:
> posterior_i <- MCMClogit(y ~ fbl.ind + fekq3 + febitda4 + fuvs + fkru
> + fzd + fur3, data=samp_i, b0=prior, B0=precision, tune=0.5) #
> calculation ergebnisse[i] <- summary(posterior_i)  # saving the
> results (works) }
> 
> --snip--
> 
> I have a data set called "daten". I produce samples of the size 200.
> The samples are saved in samp_i.
> 
> Question:
> How is the easiest way to save this samples. My code doesn't work,
> only the first column of the sample samp_i is in stichproben[i]. I
> understand why. My idea is to define a array stichproben and then save
> a matrix in the particular fields of the array. But things like y <-
> matrix(c(samp_1),nrow=200, ncol=8) and then saving y in the array
> stichproben doesn't work. How is it possible to define a matrix with
> the content of my samples (samp_i) and but them into an array
> stichproben? Or is there an easier way?

Try to look into some documentation to matrix and array. These have 
limitations that values have to be the same type, but are usually 
faster to manipulate than data frame. The behavior of objects and 
assignments depends on nature of objects. The complexity of objects 
increases in a row

vector < matrix < array < data.frame < list

and similarly changes possible ways of indexing and susetting

HTH
Petr

> 
> With kind regards
> Alex
> 
> -- 
> Alexander Geisler * Kaltenbach 151 * A-6272 Kaltenbach
> email: alexander.geisler at gmx.at | alexander.geisler at gmail.com
> phone: +43 650 / 811 61 90 | skpye: al1405ex
> 
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Petr Pikal
petr.pikal at precheza.cz