[R] Drawing schematics

[George Chen]

Hi,

I would like to represent the treatment course of a subject with an arrow representing passage through time and various ticks, arrows, or bars representing treatments done to the patient along the arrow.  I would like to generate this sort of schematic for each patient in a database taking information from the database such as time of treatment and type of treatment.

Does anybody know how I can do this?  Is there a premade R package for this sort of thing or should I try to make a new graphics function?  If a new graphics function, where could I start?

Thanks in advance.

George