We are now going to see how we can create these kinds of visualizations on our own.
We have seen that box plots are a great way of comparing the distribution of a continuous variable across different categories. As you might expect, box plots are very easy to produce using
ggplot2. The following snippet produces the box-and-whisker plot that we saw earlier, depicting the relationship between the petal lengths of the different iris species in the
> library(ggplot) > qplot(Species, Petal.Length, data=iris, geom="boxplot", + fill=Species)
First, we specify the variable on the x-axis (the iris species) and then the continuous variable on the y-axis (the petal length). Finally, we ...