This new edition of the classic book by ggplot2 creator Hadley Wickham highlights compatibility with knitr and RStudio. ggplot2 is a data visualization package for R that helps users create data graphics, including those that are multi-layered, with ease. With ggplot2, it's easy to produce handsome, publication-quality plots with automatic legends created from the plot specification, superimpose multiple layers (points, lines, maps, tiles, box plots) from different data sources with automatically adjusted common scales, add customizable smoothers that use the powerful modeling capabilities of R, such as loess, linear models, generalized additive models, and robust regression, save any ggplot2 plot (or part thereof) for later modification or reuse, and create custom themes that capture in-house or journal style requirements and that can easily be applied to multiple plots.