Importing Vector Graphics: The grImport Package for R

Abstract

This article describes an approach to importing vector-based graphical images into statistical software as implemented in a package called grImport for the R statistical computing environment. This approach assumes that an original image can be transformed into a PostScript format (i.e., the original image is in a standard vector graphics format such as PostScript, PDF, or SVG). The grImport package consists of three components: a function for converting PostScript files to an R-specific XML format; a function for reading the XML format into special Picture objects in R; and functions for manipulating and drawing Picture objects. Several examples and applications are presented, including annotating a statistical plot with an imported logo and using imported images as plotting symbols.