grid.grill(h = unit(seq(0.25, 0.75, 0.25), "npc"), v = unit(seq(0.25, 0.75, 0.25), "npc"), default.units = "npc", gp=gpar(col = "grey"), vp = NULL)
h
or v
are only given as numeric vectors.gpar
, typically the output
from a call to the function gpar
. This is basically
a list of graphical parameter settings.viewport
.