network.vertex draws regular polygons of specified radius and number of sides, at the given coordinates. This is useful for routines such as plot.network, which use such shapes to depict vertices.
References
Butts, C. T. (2008). network: a Package for Managing Relational Data in R. Journal of Statistical Software, 24(2). http://www.jstatsoft.org/v24/i02/
#Open a plot window, and place some verticesplot(0,0,type="n",xlim=c(-1.5,1.5),ylim=c(-1.5,1.5),asp=1)
network.vertex(cos((1:10)/10*2*pi),sin((1:10)/10*2*pi),col=1:10,
sides=3:12,radius=0.1)