1.4 About this book
The first chapter, Chapter 2, describes how to quickly get started using ggplot2 to make useful graphics. This chapter introduces several important ggplot2 concepts: geoms, aesthetic mappings and facetting.
Chapter 12 describes the layered grammar of graphics which underlies ggplot2. The theory is illustrated in Chapter 13 which demonstrates how to add additional layers to your plot, exercising full control over the geoms and stats used within them.
Understanding how scales work is crucial for fine-tuning the perceptual properties of your plot. Customising scales gives fine control over the exact appearance of the plot and helps to support the story that you are telling. Chapter ?? will show you what scales are available, how to adjust their parameters, and how to control the appearance of axes and legends.
Coordinate systems and facetting control the position of elements of the plot. These are described in Chapter 13.7. Faceting is a very powerful graphical tool as it allows you to rapidly compare different subsets of your data. Different coordinate systems are less commonly needed, but are very important for certain types of data.
To polish your plots for publication, you will need to learn about the tools described in Chapter 17. There you will learn about how to control the theming system of ggplot2 and how to save plots to disk.