This edition of the book was made possible by two new co-authors: Danielle Navarro and Thomas Lin Pedersen. Danielle contributed most of the new material in the layers and scales chapters, and Thomas contributed new chapters on arranging plots (using his patchwork package), and on how to extend ggplot2.

This book was written in the open and chapters were advertised on twitter when complete. It is truly a community effort: many people read drafts, fixed typos, suggested improvements, and contributed content. Without those contributors, the book wouldn’t be nearly as good as it is, and I’m deeply grateful for their help.

A big thank you to all 34 people who contributed specific improvements via GitHub pull requests (in alphabetical order by username): Alexej Gossmann (@agisga), @chriselrod, Carson Sievert (@cpsievert), Dave Childers (@davechilders), @dicorynia, Dennis Murphy (@djmurphy420), Danielle Navarro (@djnavarro), @dmurdoch, Zhuoer Dong (@dongzhuoer), Dan Yavorsky (@dyavorsky), Francisco Júnior (@fjuniorr), Gökçen Eraslan (@gokceneraslan), jashapiro (@jashapiro), Jim Hester (@jimhester), Jeffrey Girard (@jmgirard), Joel Gombin (@joelgombin), @jonas-hag, @lindbrook, @MarHer90, Mine Cetinkaya-Rundel (@mine-cetinkaya-rundel), Neil McGuigan (@neilmcguigan), Clemens Schmid (@nevrome), Pietro Monticone (@pitmonticone), Patrick Kennedy (@pkq), Robin (@Robinlovelace), Sean Hughes (@seaaan), Thomas Lin Pedersen (@thomasp85), Thomas Klebel (@tklebel), Tom Jemmett (@tomjemmett), Alex Trueman (@truemoid), Will Beasley (@wibeasley), Jake Thompson (@wjakethompson), Yang Cao (@yiluheihei), Hiroaki Yutani (@yutannihilation).