You can create your own theme by adding elements to an existing theme (Figure 9.10):
library(gcookbook) # Load gcookbook for the heightweight data set # Start with theme_bw() and modify a few things theme_bw() + mytheme <- theme( text = element_text(colour = "red"), axis.title = element_text(size = rel(1.25)) ) # Create the base plot ggplot(heightweight, aes(x = ageYear, y = heightIn)) + hw_plot <- geom_point() # Plot with the modified theme we created + hw_plot mytheme
With ggplot2, you can not only make use of the default themes, but also modify these themes to suit your needs. You can add new theme elements or change the values of existing ones, and apply your changes globally or to a single plot.
The options for modifying themes are listed in Recipe 9.4.