Hallo Everybody I have been using R for a while but I am new to using R on spatial data. What I want to do seems fairly straightforward to me but for some reason it doesn't seem to work even after reading a lot of help files and mail threads. I want to read shapefile containing a town map and subset it to contain only the polygons that correspond to a certain field in the data frame. (i.e. selelct those houses in the town for which I have some other data). I have a unique stand number in both the dataframe and shapefile. Then in want to merge some additional data from the dataframe and export back to a ESRI shapefile.
I read the shapefiles with readOGR. The resultant object (called SPbluegum) is a SpatialPolygonsDataFrame >class(SPbluegum) [1] "SpatialPolygonsDataFrame" attr(,"package") [1] "sp" I think where things go wrong is where I try to create a new object that is a subset of the full town SPDF. My code is: >SPbluegumImP=SPbluegum[which(is.na(match(SPbluegum$PROPDESC,DF$Stand.Number_0))==FALSE),c(3,4,6)] This works and can be plotted. class() reveals that this too is a SpatialPolygonsDataFrame but it cannot be written with writeOGR. This puzzles me since the error message reads:"unknown data type" > writeOGR(SPbluegumImp, dsn=paste(outdir,sep=""), layer="BluegumImpMap", > driver="ESRI Shapefile") Error in writeOGR(SPbluegumImp, dsn = paste(outdir, sep = ""), layer = "BluegumImpMap", : unknown data type Please show me where I go wrong best regards Christiaan _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo