[R] resampling mean distances

[Jose Andres]

  Hi all,

I am trying to generate a distribution for the mean euclidean  
distance between a group of n elements in a given surface (the  
elements are randomly picked).  Fo doing so I've written the  
following code:

sampling<- function(x,size) {

x<- x[sample(1:nrow(x),size),]

mat<- matrix(c(x$V6,x$V7,x$V8), ncol=3)

mean.dist<- mean(dist(mat,"euclidean"))


}

x is the file where the data are stored
size is the size of the group
mat generates a simple matrix. V6, V7, and V8 are the 3D (x,y,z)  
coordinates of the group elements .
mean.dist  calculates the mean pairwise distance between the objects  
of the group.

Everything works fine but I want  to repeat this many times (e.g.  
10000) and  store the mean.dist values in a new variable so I can   
generate the distribution of mean pairwise distances of a group of  
size n in my surface.

Is there any easy way to do this? I'd really appreciate all your  
comments.

Thanks in advance,

/Jose










On Jul 31, 2006, at 15:35, Prof Brian Ripley wrote:

> On Mon, 31 Jul 2006, Sundar Dorai-Raj wrote:
>
>>
>>
>> LL wrote:
>>> Hi.. I am running R version 2.3.1 on a Windows XP machine with  
>>> the latest Miktex 2.5 installed. I get no errors from R when  
>>> running the Sweave example,
>>>
>>> testfile <- system.file("Sweave", "Sweave-test-1.Rnw", package =  
>>> "utils")
>>>
>>> However, when I tex the resulting .tex file (after installing  
>>> a4.sty) I get the error below.
>>>
>>> This is pdfeTeX, Version 3.141592-1.30.6-2.2 (MiKTeX 2.5 RC 1)
>>> entering extended mode
>>> (Sweave-test-1.tex
>>> LaTeX2e <2005/12/01>
>>> Babel <v3.8g> and hyphenation patterns for english, dumylang,  
>>> nohyphenation, ge
>>> rman, ngerman, french, loaded.
>>> ("C:\Program Files\MiKTeX 2.5\tex\latex\base\article.cls"
>>> Document Class: article 2005/09/16 v1.4f Standard LaTeX document  
>>> class
>>> ("C:\Program Files\MiKTeX 2.5\tex\latex\base\size10.clo"))
>>> ("C:\Program Files\MiKTeX 2.5\tex\latex\ltxmisc\a4wide.sty"
>>> ("C:\Program Files\MiKTeX 2.5\tex\latex\ntgclass\a4.sty"))
>>> ! Missing \endcsname inserted.
>>> <to be read again>
>>>                    \protect
>>> l.11 \begin
>>>            {document}
>>> ?
>>> 	[[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help at stat.math.ethz.ch mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide http://www.R-project.org/posting- 
>>> guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
>> This works for me. However, when I ran this, MiKTeX prompted me to
>> install the ntgclass package, which I did. Everything ran smoothly  
>> after
>> that. I'm using R-2.3.1 with MiKTeX 2.4 in WinXP Pro.
>
> But he is using MiKTeX 2.5: looks like a problem with MiKTeX, as  
> the latex
> error is in the initial processing.
>
> -- 
> Brian D. Ripley,                  ripley at stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting- 
> guide.html
> and provide commented, minimal, self-contained, reproducible code.