Dear Simon. thanks for the tip, now it works fine best marco 2012/10/30 O'Hanlon, Simon J <simon.ohan...@imperial.ac.uk>
> Dear Marco, > You can download shapefile of the world in varying resolutions at > http://www.naturalearthdata.com/ Check under the links marked 'cultural'. > > They come with country boundaries but I think you can easily melt these > using rgeos:::gUnaryUnion > > Thanks, > > Simon > > -----Original Message----- > From: r-sig-geo-boun...@r-project.org [mailto: > r-sig-geo-boun...@r-project.org] On Behalf Of marco milella > Sent: 29 October 2012 22:12 > To: r-sig-geo > Subject: Re: [R-sig-Geo] kriging limits > > Dear Rob, > > thanks for the help. However, my shp file is a SpatialLinesDataFrame, so > things not work (blue plot). On the other hand, I tried with an old map of > Europe (SpatialPolygonsDataFrame) and it works fine. Do any of you know > where to find SpatialPolygonsDataframe .shp file of all world (possibly > without coutries boundaries)? > Thanks in advance for any feedback > marco > > 2012/10/29 Rob Robinson <rob.robin...@bto.org> > > > Marco, > > 'colouring' only the land is relatively easy, kriging over just the > > land is much harder... To do the former, all you need to to do is plot > > your kriged map, then plot a 'mask' over the sea area. To create the > > mask, you need something like the snippet below > > > > world<-readShapeSpatial("10m_coastline.shp") > > > > library(rgeos) > > g3<-readWKT("POLYGON((-180 -90,-180 90,180 90,180 -90,-180 -90))") > > sea_mask<-gDifference(g3,world) > > plot(sea_mask, col='blue', border='transparent', add=T) > > > > hope that helps > > cheers > > rob > > > > > > > > ************** Find out about Britain's birds - www.bto.org/birdfacts > > ************** > > > > Dr Rob Robinson, Principal Ecologist > > British Trust for Ornithology, The Nunnery, Thetford, Norfolk, IP24 2PU > > Ph: +44 (0)1842 750050 E: rob.robin...@bto.org > > Fx: +44 (0)1842 750030 W: > www.bto.org/about-bto/our-staff/rob-robinson > > > > ====== "How can anyone be enlightened, when truth is so poorly lit" > > ======= > > > > > > > > > > On 28 October 2012 13:25, marco milella <vru...@gmail.com> wrote: > > > >> Dear all, > >> > >> I'm a relatively new with R. However, I realized from colleagues the > >> great capabilities of R or analyzing geo data. > >> I'm interested in performing an ordinary kriging to interpolate z > >> value on a world map sarting from a dataset that (unfortunately) > >> includes rather few observations (13 locations worldwide). > >> my problems are the following: > >> > >> 1) the obtained plot extend the kriging to seas and i would like to > >> "color" > >> only lands > >> 2)I can't find a way to illustrate the kriging in a more "wave (or > >> bands) of colors rather that in a extremely smooth way as you see in > >> the attached figure > >> > >> > >> > >> below my commands > >> > >> library(maptools);library(fields);library(maps);library(geoR) > >> #here I import a .shp file representing world coastlines downloaded > >> from http://www.soest.hawaii.edu/pwessel/gshhs/index.html > >> world<-readShapeSpatial("10m_coastline.shp") > >> #now I import my dataset (value.txt), including 13 rows (each > >> location) and > >> 3 columns (Lat, Long, value) > >> dati<-read.table("value.txt",header=TRUE) > >> attach (dati) > >> s<-cbind(Long,Lat); > >> ml <- likfit(data=dati[,3],coords=s, > >> fix.nugget=F,cov.model="exponential", > >> ini = c(30, 5),nugget=5); > >> sp1<-seq(min(s[,1]),max(s[,1]),length=500); > >> sp2<-seq(min(s[,2]),max(s[,2]),length=500); > >> sp<-expand.grid(sp1,sp2); > >> inCA<-map.where("state",x=sp[,1],y=sp[,2]); > >> inCA<-inCA=="world" > >> pred<-krige.conv(data=dati[,3],coords=s,locations=sp, > >> krige=krige.control(cov.model="exponential", > >> cov.pars=c(26.19,13.7), > >> nugget=4.5763)); > >> image.plot(sp1,sp2,matrix(pred$predict,500,500),zlim=range(dati[,3])) > >> map("world",add=T) > >> > >> [[alternative HTML version deleted]] > >> > >> _______________________________________________ > >> R-sig-Geo mailing list > >> R-sig-Geo@r-project.org > >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo > >> > > > > > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
