Integrating grid Graphics Output with Base Graphics Output

The grid graphics package[1] is much more powerful than the standard R graph-ics system (hereafter“base graphics”) when it comes to combining and arranging graphical elements. It is possible to create a greater variety of graphs more easily with grid (see, for example, Deepayan Sarkar’s lattice package[2]). However, there are very many plots based on base graphics (e.g., biplots), that have not been implemented in grid, and the task of reimplementing these in grid is ex-tremely daunting. It would be nice to be able to combine the ready-made base plots with the sophisticated arrangement features of grid. This document describes the gridBase package which provides some support for combining grid and base graphics output. Annotating base graphics using grid The gridBase package has one function, baseViewports(), that supports adding grid output to a base graphics plot. This function creates a set of grid view-ports that correspond to the current base plot. This allows simple annotations such as adding lines and text using grid’s units to locate them relative to