Developing Geographic Thematic Maps with R

Answer 1

The R Graphics Gallery has a very similar map which should make for a good starting point. The code is here: www.ai.rug.nl/~hedderik/R/US2004 . You'd need to add a legend with the legend() function.

Answer 2

Take a look at the PBSmapping package (see borh the vignette/manual and the demo) and this O'Reilly Data Mashups in R article (unfortunately it is not free of charge but it worth 4.99$ to download, according Revolutions blog ).

Answer 3

Check out the packages

library(sp)
library(rgdal)

which are nice for geodata, and

library(RColorBrewer)

is useful for colouring. The map (link below) is made with those packages and this code:

VegMap <- readOGR(".", "VegMapFile")
Veg9<-brewer.pal(9,'Set2')
spplot(VegMap, "Veg", col.regions=Veg9,
 +at=c(0.5,1.5,2.5,3.5,4.5,5.5,6.5,7.5,8.5,9.5),
 +main='Vegetation map')

'VegMapFile' is a .shp and 'Veg' is the variable displayed. Can probably be done better with a little work. I don`t seem to be allowed to upload image, here is an link to the image:

link text

Answer 4

Hi,

Thought I would add some new information here since there has been some activity around this topic since the posting. Here are two great links to "Choropleth Map R Challenge" on the Revolutions blog:

Choropleth Map R Challenge

Choropleth Challenge Results

Hopefully these are useful for people viewing this question.

All the best,

Jay