Redraw Base Graphics Using 'grid' Graphics
c(person("Paul", "Murrell", role = c("cre", "aut"),
                    email = "paul@stat.auckland.ac.nz"),
             person("Zhijian", "Wen", role = "aut",
                    email = "jwen246@aucklanduni.ac.nz"))
Functions to convert a page of plots drawn with the 
  'graphics' package into identical output drawn with the 'grid' package.
  The result looks like the original 'graphics'-based plot, but consists
  of 'grid' grobs and viewports that can then be manipulated with 
  'grid' functions (e.g., edit grobs and revisit viewports).
Paul Murrell [cre, aut],
  Zhijian Wen [aut]