On Thu, 12 Apr 2007, Adriana Bejarano wrote: > This may be a trivial question for some of you: Is there a way to add > defined grid sizes on specific areas of a map?. I want to add 10kmx10km > grids to all California coastal counties: > > "california,alameda", "california,contra costa", "california,del norte", > "california,humboldt", "california,los angeles", "california,marin", > "california,mendocino" ,"california,monterey", "california,napa", > "california,orange", "california,riverside", "california,sacramento", > "california,san benito", "california,san bernardino", "california,san > diego" , "california,san francisco", "california,san joaquin", > "california,san luis obispo", "california,san mateo", "california,santa > barbara", "california,santa clara", "california,santa cruz", > "california,siskiyou", "california,solano", "california,sonoma", > "california,sutter", "california,trinity", "california,ventura", > "california,yolo" > The mapproj package has a map.grid() function, but that only allows you to specify latitude- and longitude-based grids. I don't think it would be too difficult to roll your own using standard trigonometry if you weren't too worried about the non-sphericity of the earth.
Otherwise I guess there would be something 'out there' to provide you with some conversion between lat/long and distance from a fixed point. HTH, Ray Brownrigg ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.