[R-sig-Geo] Bi- or Tri-variate maps for R

[Hisaji ONO]

Hello.

 Does anyone know any examples of Bi- or Tri-variate maps
for R like this ArcVie example?

    
http://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap171/p171.htm



 Thanks in advance.