In this recipe, we will learn how to show the density of data points on a scatter plot in the margin of the X or Y axes.
We will use the rug()
function in the base graphics library. As a simple example to illustrate the use of this function, let's see the data density of a normal distribution:
x<-rnorm(1000) plot(density(x)) rug(x)
As can be seen from this example, the rug()
function adds a set of lines just above the x-axis. A line or tick mark is placed wherever there is a point at that particular X
location. So, the more closely packed together the lines are, the higher the data density around those X
values is. The example is obvious, as we know that in a normal distribution, most values are around the mean value (in this case, zero).
The rug()
function, in its simplest form, only takes one numeric vector as its argument. Note that it draws on...