ABSTRACT
This chapter describes various standard graphics for presenting multivariate data. It discusses briefly the lattice package, a recommended package that comes bundled with R; and ggplot2, an add-on package of relatively origins. Technical differences aside, the reason for using different plot characters is the desire to represent a third variable in the graphic, in this case the categorical variable recording the species factor. The ggplot2 add-on package provides another system for plotting within R that has proven very popular. There are many benefits to making graphics with ggplot2, but perhaps the biggest is the visual appeal of the graphics produced. It is clear that considerable attention was given to all aspects of the rendering. The term geoms is short for geometric objects and refers to the functions that do the actual rendering of the data. In ggplot2’s grammer, statistical transformations summarize the data before it is rendered. The histogram is a good example.
