RG#87: histogram / bar chart over map

library(ggsubplot)
library(ggplot2)
library(maps)
library(plyr)

#Get world map info
world_map <- map_data("world")

#Create a base plot
p <- ggplot()  + geom_polygon(data=world_map,aes(x=long, y=lat,group=group), col = "blue4", fill = "lightgray") + theme_bw()

# Calculate the mean longitude and latitude per region (places where subplots are plotted),
cntr <- ddply(world_map,.(region),summarize,long=mean(long),lat=mean(lat))

# example data
 myd <- data.frame (region = rep (c("USA","China","USSR","Brazil", "Australia","India", "Canada"),5),
                    categ = rep (c("A", "B", "C", "D", "E"),7), frequency = round (rnorm (35, 8000, 4000), 0))
                   

subsetcntr  <- subset(cntr, region %in% c("USA","China","USSR","Brazil", "Australia","India", "Canada"))

simdat <- merge(subsetcntr, myd)
colnames(simdat) <- c( "region","long","lat", "categ", "myvar" )


 myplot  <- p+geom_subplot2d(aes(long, lat, subplot = geom_bar(aes(x = categ, y = myvar, fill = categ, width=1), position = "identity")), ref = NULL, data = simdat)

print(myplot)