ggplot2 custom legend shapes

Question

When we have both shape and color legend in scatter plot, the shape of color legend is misleading:

foo <- data.frame(
  length=runif(10),
  height=runif(1         


        

Answer 1

It is possible to manually change the properties of the legend using guides:

ggplot(foo, aes(x = length, y = height, color=group, shape=quality)) + 
  geom_point(size=5) + 
  guides(colour = guide_legend(override.aes = list(shape = 15)))

Just play around with the shape paramater to find an appropriate shape.