Hi Ben, My best guess based on the information you have provided is that R is running out of memory, particularly for complex polygons Unions can use a huge amount of memory. Can you check with the task manager what the memory usage looks like when running your code?
-Colin On Sep 7, 2011, at 8:26 AM, Ben Weinstein wrote: > Hi all- > > I'm having an odd issue with the gUnion family of commands from the rgeos > package. I'm importing a series of polygons (species) and trying to find the > centroid. Each species is only allowed one centroids, so i need to union the > multiple polygons. this code works great when run line by line. But when run > as an actual loop, but adding the {} at beginning and end, it gives me a > runtime error. I have debugged it to the level that i know it is the union > polygon step. I am running R 2.13, and it was designed for 2.13.1, is that > really making the difference? When run, R completely freezes and windows > shuts it down. > > library(rgdal) > library(PBSmapping) > library(maptools) > library(raster) > library(rgeos) > #Enter File Directory Below > setwd("D:/Ben/R/Trochilidae") > #Pull in all shapefiles in that folder that are polygons > a<-list.files(pattern='pl.shp$', full.names=FALSE) > output<-matrix(nrow=length(a),ncol=3) > colnames(output)<-c("Sci_Name","X_centroid","Y_centroid") > for(x in 1:length(a)){ > output[(x),1]<-paste(gsub(".shp","",a[x])) > range<-readShapePoly(a[x], delete_null_obj=TRUE) > subsetx<-range[range$PRESENCE == 1,] > subsetx2<-subsetx[subsetx$ORIGIN ==1|subsetx$ORIGIN==2,] > z<-matrix(length(subsetx2),1, data=1) > Union<-unionSpatialPolygons(subsetx2,z) > Breeding.ps<- SpatialPolygons2PolySet(Union) > Breeding.centroids<- calcCentroid(Breeding.ps, rollup=1) > output[x,2:3]<-as.matrix(Breeding.centroids[2:3])} > > thanks > > ben weinstein > > > > > -- > Ben Weinstein > Graduate Student > Ecology and Evolution > Stony Brook University > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-geo _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo