I'm using R and am trying to create a choropleth map using
GISTools. My code is like:
choropleth(us_state, us_state$smallbiz1998, shades) plot(us_interstate, add = TRUE)
us_state is a map of US states and
us_interstate is a map of the interstate highways.
I want the boundaries of US states to be in gray. How can I do this?
choropleth documentation indicates that you can specify
Additional parameters to be passed on to the plot method for sp.. However, when I try
choropleth(us_state, us_state$smallbiz1998, shades, col = "gray") it throws an error.
(If it were changing the interstate highways to be gray, it's easy, just change the second line to
plot(us_interstate, add = TRUE, col = "gray")).