Dear List,

I would like to draw lines in raster cells with a certain values, I can 
work around this with a for loop but as always this solution only works 
for small datasets (which is not my case), I would therefore like to 
have your opinion on this;

#the code
library(maptools) #to use spRbind
out<-NULL
r1<-raster(ncols=10,nrows=10)
r1[]<-sample(0:1,100,replace=TRUE)
for(i in 1:ncell(r1)){
   if(r1[i]==1){
lines<-SpatialLines(list(Lines(list(Line(matrix(c(xyFromCell(r1,i)+(res(r1)/2),xyFromCell(r1,i)-(res(r1)/2)),ncol=2,byrow=TRUE))),ID=as.character(i))))
     if(is.null(out)){
       out<-lines }
        else {out<-spRbind(out,lines)}
     }
   print(i)
}

Thank you in advance,
-- 
*HERTZOG* Lionel
2^nd year MSc Organismic Biology
s6lihert@uni-bonn.de <mailto:s6lihert@uni-bonn.de>
(+49)-0 15215149128

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