Generate a graph specification that can be fed into graphviz. A function by Rory Winston.

dotlattice.R

# generate a graph specification that can be fed into graphviz
# This function was borrowed Rory Winston: 
# http://www.theresearchkitchen.com/archives/738
dotlattice <- function(S, labels=FALSE) {
  shape <- ifelse(labels == TRUE, "plaintext", "point")

  cat("digraph G {", "\n", sep="")
  cat("node[shape=",shape,", samehead, sametail];","\n", sep="")
  cat("rankdir=LR;","\n")

  cat("edge[arrowhead=none];","\n")

  # Create a dot node for each element in the lattice
  for (i in 1:length(S)) {
    cat("node", i, "[label=\"", S[i], "\"];", "\n", sep="")
  }

  # The number of levels in a binomial lattice of length N
  # is `$\frac{\sqrt{8N+1}-1}{2}$`
  L <- ((sqrt(8*length(S)+1)-1)/2 - 1)

  k<-1
  for (i in 1:L) {
    tabs <- rep("\t",i-1)
    j <- i
    while(j>0) {
      cat("node",k,"->","node",(k+i),";\n",sep="")
      cat("node",k,"->","node",(k+i+1),";\n",sep="")
      k <- k + 1
      j <- j - 1
    }
  }

  cat("}", sep="")
}