Ok here is my latest development on the topic! But I still have a question! At the end I still get segmented polygons!
library(akima) library(maptools) library(raster) data(akima) # define de dimension of grid dimgrid=50 # Interpolate to regular grid ak.li=interp(akima$x, akima$y, akima$z, xo=seq(min(akima$x), max(akima$x), length = dimgrid),yo=seq(min(akima$y), max(akima$y), length = dimgrid),linear = TRUE, extrap=FALSE, duplicate = "mean") # Show interpolation image(ak.li) points(akima) with(akima, text(x, y, formatC(z,dig=2), adj = -0.1)) # Create a raster with the data r <- raster(nrow=length(ak.li$y), ncol=length(ak.li$x), crs=NA) xmin(r) <- min(ak.li$x, na.rm=TRUE) xmax(r) <- max(ak.li$x, na.rm=TRUE) ymin(r) <- min(ak.li$y, na.rm=TRUE) ymax(r) <- max(ak.li$y, na.rm=TRUE) tmp=ak.li$z tmp=apply(tmp, 1, rev) r[] <- tmp # Show the raster plot(r) # Convert the data found between ]20 and 25[ into polygons pol <- rasterToPolygons(r, fun=function(x){x>20 & x<25}) # Show the polygons plot(pol, add=T, col='red') # Attempt to merge similar adjacent into one polygon union = unionSpatialPolygons(pol, ID=rep(1, times=length(p...@polygons))) # Show plot(union, add=TRUE, col="red") All polygons were not merged into a single one and I don't know how to fix that! Any help? _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo