R: Data Analysis and Visualization

Showing the number of observations

It is often useful to know the number of observations for each variable or group when comparing them on a box plot. We did this earlier with the varwidth argument that makes the widths of boxes proportional to the square root of the number of observations. In this recipe, we will learn how to display the number of observations on a box plot.

Getting ready

We will continue using the base graphics library functions, so we need not load any additional library or package. We just need to run the recipe code at the R prompt. We can also save the code as a script to use it later. Here, we will use the metals.csv example dataset again:

metals<-read.csv("metals.csv")

How to do it...

Once again, let's use the metal concentrations ...