1.6 Other resources
This book teaches you the elements of ggplot2’s grammar and how they fit together, but it does not document every function in complete detail. You will need additional documentation as your use of ggplot2 becomes more complex and varied.
The best resource for specific details of ggplot2 functions and their arguments will always be the built-in documentation. This is accessible online, https://ggplot2.tidyverse.org/reference/index.html, and from within R using the usual help syntax. The advantage of the online documentation is that you can see all the example plots and navigate between topics more easily.
If you use ggplot2 regularly, it’s a good idea to sign up for the ggplot2 mailing list, http://groups.google.com/group/ggplot2. The list has relatively low traffic and is very friendly to new users. Another useful resource is stackoverflow, http://stackoverflow.com. There is an active ggplot2 community on stackoverflow, and many common questions have already been asked and answered. In either place, you’re much more likely to get help if you create a minimal reproducible example. The reprex package by Jenny Bryan provides a convenient way to do this, and also include advice on creating a good example. The more information you provide, the easier it is for the community to help you.
The number of functions in ggplot2 can be overwhelming, but RStudio provides some great cheatsheets to jog your memory at http://www.rstudio.com/resources/cheatsheets/.
Finally, the complete source code for the book is available online at https://github.com/hadley/ggplot2-book. This contains the complete text for the book, as well as all the code and data needed to recreate all the plots.