While looking around at different mapping packages, I found a cool package that pulls map data off of Google Maps, allowing you to make really nice looking figures. Some of the cool things you can do include making bubble maps, like this one of cadmium levels around the river Meuse in the Netherlands:
library(sp) data("meuse", package = "sp", envir = environment()) m<-bubbleMap(meuse,zcol='cadmium');
Or color-coded maps, like this one showing leukemia levels in upstate NY in the early 1980’s.
library(RgoogleMaps) data("NYleukemia", envir = environment()) population <- NYleukemia$data$population cases <- NYleukemia$data$cases mapNY <- GetMap(center=c(lat=42.67456,lon=-76.00365), destfile = "NYstate.png", maptype = "hybrid", zoom=8) ColorMap(100*cases/population, mapNY, NYleukemia$spatial.polygon, nclr=9,add = FALSE, alpha = 1, log = TRUE, location = "bottomleft")
This blog post was super useful to explore beyond the basics of RgoogleMaps.