library(igraph)
g1 <- graph( edges=c(1,2, 2,3, 3, 1), n=3, directed=T )
plot(g1)

g3 <- graph( c("John", "Jim", "Jim", "Jill", "Jill", "John"))
plot(g3)


g4 <- graph( c("John", "Jim", "Jim", "Jack", "Jim", "Jack", "John", "John"), 
             isolates=c("Jesse", "Janis", "Jennifer", "Justin") )  

plot(g1, edge.arrow.size=.7, vertex.color="blue", vertex.size=10, 
     vertex.frame.color="black", vertex.label.color="black", 
     vertex.label.cex=0.8, vertex.label.dist=3, edge.curved=0,
     layout=layout_with_fr)