DB <- as.matrix(c(‘Argentina’, ‘Brazil’, ‘Chile’, ‘Uruguay’, ‘Paraguay’, ‘Bolivia’, ‘Peru’))

#add population-density Data

DB <- cbind (DB, c(15,23,22,19,17,10,24))

#create a gradual palette of Reds. Function belongs to RColorBrewer

gama <- brewer.pal(6,”Reds”)
countries <- as.character(DB[,1])

# with the cut function you can assign numeric values to a certain interval defined by the user (in this case 0,5,10,15,20,max(DB))

DB <- cbind(DB, cut (as.numeric(DB[,2]),c(0,5,10,15,20,max(DB)),labels = FALSE, right = TRUE))

#With the ordinal values assigned to each country, we now create a character array with the colour code corresponding to each of them, based upon the palette we have created

col <- character()

for (i in 1:nrow(DB))
{
col <- append(col,gama[as.numeric(DB[i,3])])
}

#We draw the map. Please note that the arrays countries and col need to be maintained in the same order. If not, the colour assigned to each country will be wrong. So, be careful if you need to sort the values of any array before plotting.

map(‘worldHires’,countries,fill=TRUE,col=col,plot=TRUE, cex = 15, exact=TRUE)
legend(“bottomright”, c(“up to 15”, “16 – 17”, “18 – 19”, “20-21”, “22-23”, “more than 23”),border=gama, fill = gama, cex = 1.3, box.col = “white”)

#Although RStudio (I do not know of other interfaces) provides an interface option to import a plot to a file, if you have to export the map, I would advise doing it per CLI, as the sizes and proportions are much easier to handle. In this case, it would be as follows:

png(file= (your Path),width = (width in pixels), height = (height in pixels), res = 120)
map(‘worldHires’,countries,fill=TRUE,col=col,plot=TRUE, cex = 15, exact=TRUE)
legend(“bottomright”, c(“up to 15”, “16 – 17”, “18 – 19”, “20-21”, “22-23”, “more than 23”),border=gama, fill = gama, cex = (the size you want for the box), box.col = “white”)
dev.off()