In this post, I will present a way to plot a European Union map using R. We ran across this question with @gVermandel.

EDIT (2013-02-18) : As mentioned in the comment section below, there is a nice package I wasn’t aware of, that does (with more ease and offering a more beautiful result) the same thing: https://github.com/briatte/kmaps.

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.

library(ggplot2)
library(grid)
library(rworldmap)

First, let’s get the coordinates of every countries from the getMap function. We need the names of the 28 member states of the E.U..

# Get the world map
worldMap <- getMap()

# Member States of the European Union
europeanUnion <- c("Austria","Belgium","Bulgaria","Croatia","Cyprus",
                   "Czech Rep.","Denmark","Estonia","Finland","France",
                   "Germany","Greece","Hungary","Ireland","Italy","Latvia",
                   "Lithuania","Luxembourg","Malta","Netherlands","Poland",
                   "Portugal","Romania","Slovakia","Slovenia","Spain",
                   "Sweden","United Kingdom")
# Select only the index of states member of the E.U.
indEU <- which(worldMap$NAME%in%europeanUnion)

Then we can get the coordinates for each country.

# Extract longitude and latitude border's coordinates of members states of E.U. 
europeCoords <- lapply(indEU, function(i){
  df <- data.frame(worldMap@polygons[[i]]@Polygons[[1]]@coords)
  df$region =as.character(worldMap$NAME[i])
  colnames(df) <- list("long", "lat", "region")
  return(df)
})

europeCoords <- do.call("rbind", europeCoords)

For the purpose of this example, we’ll assign some random values to each country.

# Add some data for each member
value <- sample(x = seq(0,3,by = 0.1), size = length(europeanUnion),
                replace = TRUE)
europeanUnionTable <- data.frame(country = europeanUnion, value = value)
europeCoords$value <- europeanUnionTable$value[match(europeCoords$region,europeanUnionTable$country)]

Finally, we can plot the map.

# Plot the map
P <- ggplot() + geom_polygon(data = europeCoords, aes(x = long, y = lat, group = region, fill = value),
                             colour = "black", size = 0.1) +
  coord_map(xlim = c(-13, 35),  ylim = c(32, 71))

P <- P + scale_fill_gradient(name = "Growth Rate", low = "#FF0000FF", high = "#FFFF00FF", na.value = "grey50")


P <- P + theme(#panel.grid.minor = element_line(colour = NA), panel.grid.minor = element_line(colour = NA),
               #panel.background = element_rect(fill = NA, colour = NA),
               axis.text.x = element_blank(),
               axis.text.y = element_blank(), axis.ticks.x = element_blank(),
               axis.ticks.y = element_blank(), axis.title = element_blank(),
               #rect = element_blank(),
               plot.margin = unit(0 * c(-1.5, -1.5, -1.5, -1.5), "lines"))

Member Countries of the European Union (Warning: fake data)

The legend title is a bit too close to the legend keys to my opinion… As suggested by Ronald Burggraaf (thank you!), a way to add some space between these elements is by adding a breakline character to the title :

P <- P + scale_fill_gradient(name = "Growth Raten", low = "#FF0000FF", high = "#FFFF00FF", na.value = "grey50")