Hans, Take a look at the proj4 package, specifically project()
see http://trac.osgeo.org/proj/ There are many projections that allow you to recenter a map on a specific longitude For example x <- seq(-180, 180) y <- seq(-90, 90) xy <- expand.grid(x, y) plot(xy) mer <- cbind(0, y) #prime meridian points(mer[,1], mer[,2], col = "white") proj.xy <- project(xy, "+proj=eck4") ###project grid into eckert IV proj.mer <- project(mer, "+proj=eck4") ###project meridian into eckert IV plot(proj.xy) points(proj.mer[,1], proj.mer[,2], col = "white") proj.xy <- project(xy, "+proj=eck4 +lon_0=90W") ###project grid into eckert IV with central meridian at 90W proj.mer <- project(mer, "+proj=eck4 +lon_0=90W") ###project meridian into eckert IV with central meridian at 90W plot(proj.xy) points(proj.mer[,1], proj.mer[,2], col = "white") On Thu, Jan 8, 2009 at 4:07 AM, Hans-Jörg Bibiko <bib...@eva.mpg.de> wrote: > Hi, > > I wonder if there's a workaround to generate seamless maps based on > SpatialPolygons objects. E.g. to produce a map showing Australia at the left > edge and America at the right one ( xlim := min: 110°E , max: 30°W ). > Or the way around, is there a function to re-center a given map by defining > the median longitude? (I know the function 'recenter' which produce a map > from 0° to 360°) > > Kind regards, > > --Hans > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > -- Matthew J. Oliver Assistant Professor College of Marine and Earth Studies University of Delaware 700 Pilottown Rd. Lewes, DE, 19958 302-645-4079 http://www.ocean.udel.edu/people/profile.aspx?moliver [[alternative HTML version deleted]]
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