No polytomies allowed?

I have recently been in a position to want an efficient way to obtain a binary Newick-format tree from a Newick-format tree that may or may not have polytomies.  Using a few functions from ape, this was fairly simple to obtain:


makebinary = function(newick) {
  tree = read.tree(text = newick)
  if(is.binary.tree(tree)) {
    return(newick)
  } else {
    return(write.tree(multi2di(tree)))
  }
}


This contains three very useful functions from ape:  read.tree, write.tree, is.binary.tree, and multi2di.  The first two are used to read/write Newick-format trees.  The functions read.nexus and write.nexus can be used for Nexus-format trees.  read.tree can be used for files as well.  is.binary.tree checks whether a tree has any polytomies, and multi2di converts a tree with multichotomies to a fully dichotomous tree with some branches of length 0.  There is also a function di2multi that will collapse any branches less than a tolerance level to a polytomy.