[R] Simulation in R - Part 2

[Petr Pikal]

Hi

from write.csv help page:
x the object to be written, preferably a matrix or data frame. If 
not, it is attempted to coerce x to a data frame. 

So array is not a kind of object which can be saved as you want 
without some complication. Basically it is a plain vector with dim 
attributes and write.csv do its best to coerce it to data frame, but 
here you definitely need to do the transformation on your own.

You either shall use list and then transfer it to data frame by

do.call(rbind, the.list) # or something similar

or try to reshape your array e.g. by using melt and cast from reshape 
package to the form suitable for data frame transformation.

HTH
Petr



On 7 Dec 2006 at 22:33, Alexander Geisler wrote:

Date sent:      	Thu, 07 Dec 2006 22:33:05 +0100
From:           	Alexander Geisler <alexander.geisler at gmail.com>
To:             	r-help at stat.math.ethz.ch
Subject:        	[R] Simulation in R - Part 2

> Hello!
> 
> So, the simulation works (drawing 100 samples and then calculate the
> model for each sample). Here is the code:
> 
> --snip--
> # sample size n=200
> ergebnisse200 <- rep(0, each=100)
> stichproben200 <- vector(“list”, 100)
> default200 <- rep(0, each=100)
> 
> for (i in seq(1:100)) {
> n <- dim(daten)[1]  	
> ix <- sample(n,200) 	
> samp_i <- daten[ix,]  	# draw samples
> y <- sum(samp_i$y)     # number of defaults
> stichproben200[[i]] <- samp_i  # saving the samples
> default200[i] <- y   # saving the number of defaults
> 
> # Modell berechnen:
> posterior_i <- MCMClogit(y ~ fbl.ind + fekq3 + febitda4 + fuvs + fkru
> + fzd + fur3, data=samp_i, b0=prior, B0=precision, tune=0.5) #
> calculation ergebnisse200[i] <- summary(posterior_i)  # saving the
> results }
> 
> # write out the solutions into an excel-file
> write.csv2(ergebnisse200, "ergebnisse.csv")
> --snip--
> 
> My solution has the following form:
> 
> http://img296.imageshack.us/my.php?image=ergebnissewa0.jpg
> 
> write.csv2 makes the right thing, but in the excel-file, if I open the
> csv-file in excel, several objects are next to each other (I'm missing
> the line break after each object of the array); look at
> http://img67.imageshack.us/my.php?image=ergebnisseexcelbg7.jpg The
> problem is that there is an error message by importing the csv in
> excel, because there are to many columns needed to import the 100
> objects.
> 
> So, my question:
> Is it possible to write the 100 objects of the array among each other.
> Like as it can be seen in R
> (http://img296.imageshack.us/my.php?image=ergebnissewa0.jpg)? Another
> way is to produce 50 samples in a first turn and then produce 50
> samples again in another turn, but this can not be a "clean" solution
> (and surely not the only one).
> 
> Hopefully you can help me and this is the last question for my
> simulation.
> 
> Thanks for your efforts
> 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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> PLEASE do read the posting guide
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> minimal, self-contained, reproducible code.

Petr Pikal
petr.pikal at precheza.cz