添加法国，它位于右下方，因此我们应该看到一点…

plot(FR,add=TRUE)

然后，我们可以检索英国退欧公投数据

referendum=ddply(referendum,.(Region,HASC_code),summarise,Remain=sum(Remain),Leave=sum(Leave))

我们可以发现，脱欧赢得了51.89％的选票

> sum(referendum$Leave)/(sum(referendum$Leave)+sum(referendum$Remain)) [1] 0.5189184

大家可以看一下，使用

plot(UK, col = map_data$Brexit, border = "gray1", xlim = c(-4,-2), ylim = c(50, 59), main="How the UK has voted?", bg="#A6CAE0") plot(IRL, col = "lightgrey", border = "gray1",add=TRUE) plot(FR, col = "lightgrey", border = "gray1",add=TRUE)

(我们添加了一个小图例以使其更清晰)。为此，我们可以使用制图软件包

plot(UK, col = "grey", border = "gray1", xlim = c(-4,-2), ylim = c(50, 59),bg="#A6CAE0") plot(IRL, col = "lightgrey", border = "gray1",add=TRUE) plot(FR, col = "lightgrey", border = "gray1",add=TRUE) choroLayer(spdf = UK, df = map_data, var = "Percentage_Remain", breaks = seq(0,100,10), col = cols, legend.pos = "topright", legend.title.txt = "", legend.values.rnd = 2, add = TRUE)