Rectangular ggplot2 geom_point shape

Question

I came across this question which had a really cool graph . I am interested in the graphs on the left with the rectangular points across time.

These rectangular points are not part of R's default set of points to give the geom_point() command. While I can reproduce the graph (or at least one very similar) I don't know how to get the points to look like that.

How can I achieve this?

Answer 1

It seems to me that's just geom_tile, not geom_point in target plot.

require("ggplot2")

ggplot(iris) + geom_tile(aes(x = Sepal.Length, y = Sepal.Width, 
                             fill = Petal.Length), color = "white") + 
  facet_grid(Species ~ .) + 
  scale_fill_gradient(low = "red3", high = "blue4")