原文链接：http://tecdat.cn/?p=13247

本文我们绘制英国脱欧投票的地图。第一步是绘制底图

library(sp)

library(raster)

download.file("http://biogeo.ucdavis.edu/data/gadm2.8/rds/GBR_adm2.rds","GBR_adm2.rds")

UK=readRDS("GBR_adm2.rds")

UK@data[159,"HASC_2"]="GB.NR"

plot(UK, xlim = c(-4,-2), ylim = c(50, 59), main="UK areas")

添加爱尔兰

plot(IRL,add=TRUE)

 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)