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

Not a complete answer, but I think you need to play with guides.

ggplot(legendGoal, 
       aes(Var1,Var2,
           col=as.factor(value),
           fill=as.factor(value))) +
  geom_tile() +
  guides(col = guide_legend(nrow = 3))