[R] Eval to write many files

Uwe Ligges ligges at statistik.tu-dortmund.de
Wed Apr 27 14:30:04 CEST 2011

On 27.04.2011 13:59, Alaios wrote:
> Dear all
> I am looking for a shorter way and more elegant to write the following
> for (i in c(1:length(Shadowlist))){
>    filename<-paste('/home/apa/maps/',model,i,'.mat',sep="")
>    varname<-paste(model,'_shadow',i,sep="")
>    eval(parse(text=paste('writeMat(filename,',varname,'=Shadowlist[[i]])',sep="")))
> }

Won't be much shorter, but in loops use
seq_alonmg(Shadowlist) rather than c(1:length(Shadowlist))
In the latter, the c() is useless and 1:length(.) may become 1:0 for a 
length 0 object.

Actually I'd try:

     sa <- seq_along(Shadowlist)
     filenames <- paste('/home/apa/maps/', model, sa, '.mat', sep="")
     names(Shadowlist) <- paste(model, '_shadow', sa, sep="")
     for(i in sa)
         do.call(writeMat, c(con = filenames[i], Shadowlist[i]))

Uwe Ligges

> actually I do not like eval at the end but I wanted to control the varname inside the writeMat command
> writeMat(filename,varname=Shadowlist[[i]])
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