Welcome in the density plot section of the gallery. If you want to know more about this kind of chart, visit data-to-viz.com. If you're looking for a simple way to implement it in R, pick an example below.
ggplot2 library
A
density plot
shows the distribution of a numeric variable. In
ggplot2, the geom_density() function takes
care of the kernel density estimation and plot the results. A
common task in dataviz is to compare the distribution of several
groups. The
graph #135 provides a few
guidelines on how to do so.