Many people have contributed to this book with high-level structural insights, spelling and grammar corrections and bug reports. I’d particularly like to thank William E. J. Doane, Alexander Forrence, Devin Pastoor, David Robinson, and Guangchuang Yu, for their detailed technical reviews of the book.

Many others have contributed over the (now quite long!) lifetime of ggplot2. I would like to thank: Leland Wilkinson, for discussions and comments that cemented my understanding of the grammar; Gabor Grothendieck, for early helpful comments; Heike Hofmann and Di Cook, for being great advisors and supporting the development of ggplot2 during my PhD; Charlotte Wickham; the students of stat480 and stat503 at ISU, for trying it out when it was very young; Debby Swayne, for masses of helpful feedback and advice; Bob Muenchen, Reinhold Kliegl, Philipp Pagel, Richard Stahlhut, Baptiste Auguie, Jean-Olivier Irisson, Thierry Onkelinx and the many others who have read draft versions of the book and given me feedback; and last, but not least, the members of R-help and the ggplot2 mailing list, for providing the many interesting and challenging graphics problems that have helped motivate this book.

Hadley Wickham
September 2015