ggplot2, graphics, grDevices, grid, gridGraphics, rvcheck
ggplot2, graphics, grDevices, grid, gridGraphics, yulab.utils
colorspace, cowplot, ggimage, knitr, lattice, prettydoc, vcd
aplot, colorspace, cowplot, ggimage, knitr, rmarkdown,
lattice, prettydoc, vcd, utils