Chapter 4 Different types of plots

What I cannot create, I do not understand.
Richard Feynman

There are a few different plotting packages in R, but the most elegant and versatile one is ggplot2¹¹. gg stands for grammar of graphics which means that we can make a plot by describing it one component at a time. In other words, we build a plot by adding layers to it.

This does not have to be many layers, the simplest ggplot() consists of just two components:

• the variables to be plotted;
• a geometrical object (e.g., point, line, bar, box, etc.).

ggplot() calls geometrical objects geoms.

Figure 4.1 shows some example steps for building a scatter plot, including changing its appearance (‘theme’) and faceting - an efficient way of creating separate plots for subgroups.

FIGURE 4.1: Example steps for building and modifying a ggplot. (1) Initialising the canvas and defining variables, (2) adding points, (3) colouring points by continent, (4) changing point type, (5) faceting, (6) changing the plot theme and the scale of the x variable.

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11. The name of the package is ggplot2, but the function is called ggplot(). For everything you’ve ever wanted to know about the grammar of graphics in R, see Wickham (2016).↩︎