Gianni, If you read a points shpfile to get a SpatialPointsDataFrame object (via maptools or readOGR) then, if your object is called 'x'
pts = coordinates(x) # this will return something like: pts <- rbind(c(-180,-20), c(-140,55), c(10, 0), c(-140,-60)) # you need to make sure that the last point and first coincide, so perhaps do pts = rbind(pts, pts[1,]) # and then something like this sp = SpatialPolygons( list( Polygons(list(Polygon(pts)), 1))) plot(sp) points(pts, col='red', pch=as.character(0:9), cex=2) And you can use writeOGR to save 'sp' as a shapefile. Of course this assumes that the points are in the right order. Also, you might prefer to read in the points from a text file rather then going through a shapefile. Robert On Wed, Feb 10, 2010 at 6:24 PM, gianni lavaredo <gianni.lavar...@gmail.com> wrote: > dear R users, > > there is same possibility to convert a points shape file in a polygon shape > file? where the corner are the last points > > thanks > gianni > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo