Choropleth map in R

Map_pwt.R

#
# Map the 'Purchasing Power Parity (PPP) 
# converted GDP per capita' from pwt7.0
# using a shapefile
#

library(maptools)
library(pwt)
library(classInt)

# Download a worldmap as shapefile from
# http://thematicmapping.org/downloads/world_borders.php
wshp <- readShapeSpatial("TM_WORLD_BORDERS-0.3.shp")

head(wshp@data)

plot(wshp, lwd=1)

# rownames as ID
wshp@data$ID <- rownames(wshp@data)

# using data from the Penn World Tables - year "2008"
data("pwt7.0")
z <- pwt7.0[pwt7.0$year == "2008", ]

o <- match(wshp@data$ISO3, z$isocode)
z1 <- z[o, ]
row.names(z1) <- wshp@data$ID

# 'cbind' shapefile and data.frame
wshp1 <- spCbind(wshp, z1)

head(wshp1@data)

# set colour
mypal <- c("wheat1", "red3")

# PPP converted GDP per capita, Geary-Khamis (G-K) method, 
# at current prices (in International dollar).
v <- classIntervals(wshp1@data$cgdp, n=5, style="quantile")

wshp1@data$xcol <- findColours(v, mypal)

plot(wshp1, col = wshp1@data$xcol, lwd=1)

invisible(title(main="PPP converted GDP per capita - 2008, 5 Quantile", cex.main = 0.8))

#
# FINI
#