Visualizing distributions of some measured quantity is an extremely common task in bioinformatics, and one that base R handles admirably with its hist() and density() functions and the generic plot() methods, which can create plots of the objects. The ggplot graphics system has a neat way of plotting many density graphs in a per factor level manner, resulting in a compact and very readable graphic—a so-called ridgeplot. In this recipe, we'll look at how to create a ridgeplot.