Ggplot2 is built on Grid Graphics, which is a well thought-out low level graphics layer. Part of the reason so many extensions to ggplot2 get built, is because

Ggplot2 is built on Grid Graphics, which is a well thought-out low level graphics layer. Part of the reason so many extensions to ggplot2 get built, is because Grid is easy (albeit lower level) to work with. https://cran.r-project.org/web/packages/gridGraphics/ https://cran.r-project.org/web/packages/gridGraphics/ I've said it before, but the attempts to replicate ggplot2 usually fail to implement the full stack. As a result we have somewhat incomplete implementations of surface features of ggplot2, without the depth that is afforded by the grid / ggplot2 combo.