For this recipe, we don't need to load any additional libraries. We just need to type the recipe in the R prompt or run it as a script.

Let's say we want to highlight one data point in the cars' scatter plot that we used in the previous few recipes. We can label it using the text() command:

plot(mpg~disp, data=mtcars)
text(258,22,"Hornet")

In the preceding example, we first plotted the graph and then used the text() function to overlay a label at a specific location. The text() function takes the x and y coordinates and the text of the label as arguments. We specified the location as (258,22) and the label text as Hornet. This function is especially useful when we want to label outliers.

We can also use the text() function to label all the data points in a graph instead of just one or two. Let's look at another example where we...