Choropleth world map

Question

I have read so many threads and articles and I keep getting errors. I am trying to make a choropleth? map of the world using data I have from the global terrorism database. I wa

Answer 1

Building on the nice work by @jlhoward. You could instead use rworldmap that already has a world map in R and has functions to aid joining data to the map. The default map is deliberately low resolution to create a 'cleaner' look. The map can be customised (see rworldmap documentation) but here is a start :

library(rworldmap)

#3 lines from @jlhoward 
gtd        <- read.csv("globalterrorismdb_1213dist.csv")
gtd.recent <- gtd[gtd$iyear>2009,]
gtd.recent <- aggregate(nkill~country_txt,gtd.recent,sum)

#join data to a map
gtdMap <- joinCountryData2Map( gtd.recent, 
                               nameJoinColumn="country_txt", 
                               joinCode="NAME" )

mapDevice('x11') #create a world shaped window

#plot the map
mapCountryData( gtdMap, 
                nameColumnToPlot='nkill', 
                catMethod='fixedWidth', 
                numCats=100 )

Following a comment from @hk47, you can also add the points to the map sized by the number of casualties.

deaths <- subset(x=gtd, nkill >0)

mapBubbles(deaths,
           nameX='longitude',
           nameY='latitude', 
           nameZSize='nkill', 
           nameZColour='black',
           fill=FALSE, 
           addLegend=FALSE, 
           add=TRUE)