In this post, I will present a way to plot a European Union map using R. As you know, some countries are missing in the maps package. So, instead of working with that package, we will use the rworldmap one, available on CRAN. We will also need two more packages : ggplot2 and grid.
After some research on the Internet, I gave up trying to find an R function to add a scale bar and a North arrow on a map, using ggplot().
So, I would like to present you what I have come up with.
The idea is really basic : we create two polygons for the scale bar, we add some text above, and we draw an arrow. That’s it. The only tricky thing here, is the way to obtain the coordinates of each element. An easy solution is to use the gcDestination function, from the maptools package.