Converting a "map" object to a "SpatialPolygon" object
Just found some code in the text "Applied Spatial Data Analysis with R". It works great!
require(maps)usa <- map("state", fill = TRUE)require(sp)require(maptools)IDs <- sapply(strsplit(usa$names, ":"), function(x) x[1])usa <- map2SpatialPolygons(usa, IDs=IDs, proj4string=CRS("+proj=longlat +datum=WGS84"))