[R] Exporting to file: passing source name to file name in loop

[Prof Brian Ripley]

What does `it doesn't work' actually mean?  Please read the posting guide
and follow its advice.

Also, please show us readable and properly indented code, using spaces 
consistently.  (There is a chapter in `Writing R Extensions' showing you 
how to do this.)  I just cannot parse your code, and suspect you cannot 
either.

On Sun, 14 Nov 2004, Laura Quinn wrote:

> Hi,
>
> I'm having a mental block as to how I can automatically assign filenames
> to the output of the following code. I am wishing to create a separate
> .png file for every image created, each of them having a sequential
> filename ie "sourcefile_index.png" so that I can create a movie from
> them.
>
> Please could someone tell me where I am going wrong?
>
> the following code works fine and outputs to screen:
>
> fun_pca_vector_movie_plot<-function(x,y,z,t){
> zz=seq(1,(nrow(x)-t),by=t);jj=seq(t+1,(nrow(x)),by=t)
> for(i in seq(along=zz)){
>         pca<-prcomp(x[zz[i]:jj[i],], retx=T, center=T,scale=T)
>        {
>     par(mfrow=c(1,z))
>      for(i in 1:z){
>       image(east,north,t(map.matrix),col=my.colors,axes=T,
>           xlab="",ylab="")
>       text(y[,3],y[,2],labels=as.character(y[,1]))
>       title(paste("Component",i,"Step:"))
>        arrows(y[,3],y[,2],(y[,3]+50*(pca$rotation[i,1:(ncol(x)/2)])),
>        (y[,2]+50*(pca$rotation[i,((ncol(x)/2)+1):(ncol(x))])),
>        angle=30,length=0.05,code=2)
>      }
>     box()
>    }
>   }}
>
> but when I try to save to file as follows it doesn't work:
>
> fun_pca_vector_movie_plot<-function(x,y,z,t){
> zz=seq(1,(nrow(x)-t),by=t);jj=seq(t+1,(nrow(x)),by=t)
> for(i in seq(along=zz)){
>      pca<-prcomp(x[zz[i]:jj[i],], retx=T, center=T,scale=T)
>    {
>     par(mfrow=c(1,z))
>       for(i in 1:z){
>       plot.new()
>       png(file=(paste(x".",i,"_",zz,".png",sep="")),width=240,height=240)
>       image(east,north,t(map.matrix),col=my.colors,axes=T,
>           xlab="",ylab="")
>       text(y[,3],y[,2],labels=as.character(y[,1]))
>       title(paste("Component",i,"Step:"))
>        arrows(y[,3],y[,2],(y[,3]+50*(pca$rotation[i,1:(ncol(x)/2)])),
>        (y[,2]+50*(pca$rotation[i,((ncol(x)/2)+1):(ncol(x))])),
>        angle=30,length=0.05,code=2)
>       dev.off()
>      }
>     box()
>    }
>   }}
>
> many thanks in advance!
> Laura Quinn
> Institute of Atmospheric Science
> School of Earth and Environment
> University of Leeds
> Leeds
> LS2 9JT
>
> tel: +44 113 343 1596
> fax: +44 113 343 6716
> mail: laura at env.leeds.ac.uk
>
> ______________________________________________
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> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
>
>

-- 
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