[R-sig-Geo] Load a map png in ggplot2 (workaround for missing world map support in ggmap)

Hello everybody, my professor and I are assembling a handout on the best options for creating maps in R. As it looked very up-to-date, I've been considering including a short tutorial on the ggmap package. Now, as some of you might have noticed, the ggmap package does not fully support

[R-sig-Geo] Which are the most suitable, elegant or efficient packages for geographical maps in R? Which did you use yourself?

Hi everyone. I remember some very interesting and professional-looking R projects that somehow involved geographical maps. Now that I'd like to work with maps myself, let me ask you this question: Which of the packages that are currently available would you think are the most elegant and