Review of Basic Data Analytic Methods Using R - Data Science and Big Data Analytics - page 131

Figure 3.14 Dotplot to visualize multiple variables
The barplot in Figure 3.15 visualizes the distribution of car cylinder counts and
number of gears. The x-axis represents the number of cylinders, and the color
represents the number of gears. The code to generate Figure 3.15 is shown next.
counts <- table(mtcars$gear, mtcars$cyl)
barplot(counts, main="Distribution of Car Cylinder Counts
and Gears",
xlab="Number of Cylinders", ylab="Counts",
col=c("#0000FFFF", "#0080FFFF", "#00FFFFFF"),
legend = rownames(counts), beside=TRUE,
args.legend = list(x="top", title = "Number of Gears"))