Chapter 2. Quickly Exploring Data
Although I’ve used the ggplot2 package for most of the graphics in this book, it is not the only way to make graphs. For very quick exploration of data, it’s sometimes useful to use the plotting functions in base R. These are installed by default with R and do not require any additional packages to be installed. They’re quick to type, are straightforward to use in simple cases, and run very quickly.
If you want to do anything beyond very simple graphs, though, it’s generally better to switch to ggplot2. This is in part because ggplot2 provides a unified interface and set of options, instead of the grab bag of modifiers and special cases required in base graphics. Once you learn how ggplot2 works, you can use that knowledge for everything from scatter plots and histograms to violin plots and maps.
Each recipe in this section shows how to make a graph with base
graphics. Each recipe also shows how to make a similar graph with the
qplot() function in ggplot2, which has a syntax similar to the base
graphics functions. For each
graph, there is also an equivalent using the more powerful
If you already know how to use base graphics, having these examples side by side will help you transition to using ggplot2 for when you want to make more sophisticated graphics.
Creating a Scatter Plot
You want to create a scatter plot.
To make a scatter plot (Figure 2-1), use
plot() and pass it a vector of x values followed by a vector ...