Make a 2D legend for a plot - bi-variate choropleth maps

Question

I have been playing with bi-variate choropleth maps and have gotten stuck on how to create a 2d legend similar to the one by Joshua Stevens shown here:

To illus

Answer 1

Okay, last update. The white space between columns bugs me and the grid feature of cowplot will let us use a shrunken plot as our bi-variate legend, like so:

library(ggplot2)
library(cowplot)
library(reshape2)
#use color scheme shown here http://www.joshuastevens.net/cartography/make-a-bivariate-choropleth-map/
bvColors=c("#be64ac","#8c62aa","#3b4994","#dfb0d6","#a5add3","#5698b9","#e8e8e8","#ace4e4","#5ac8c8")
melt(matrix(1:9,nrow=3))
legendGoal=melt(matrix(1:9,nrow=3))
test<-ggplot(legendGoal, aes(Var2,Var1,fill = as.factor(value)))+ geom_tile()
test<- test + scale_fill_manual(name="",values=bvColors)
test<-test + theme(legend.position="none")
#test<-ggdraw(test) + draw_text(text = "More Var 2 -->",x=0.91,y=0.58)
#test<-ggdraw(test) + draw_text(text = "More Var 1 -->",x=0.84,y=0.5,angle=270)

#create a plot that will be the legend itself
lg<- test #would not be true when making a map
lg<-lg + theme(axis.title.x=element_text(size=rel(1),color=bvColors[3])) + xlab("More Var2 -->")
lg<-lg + theme(axis.title.y=element_text(size=rel(1),color=bvColors[3])) + ylab("More Var1 -->")
lg<-lg+theme(axis.text=element_blank())
lg<-lg+theme(line=element_blank())
#put both plots on a grid
ggdraw()+ draw_plot(lg,0.1,0.7,width=0.2,height=0.2) +draw_plot(test,0.3,0,width=.7,height=.7)

Pretty, yes?