[igraph] Upside-Down Trees and Vertex Size

[Aaron Arvey]

Hi,

First, thanks for the great network library!

Second, I'm trying to create a tree similar to the one found at:

http://en.wikipedia.org/wiki/Alternating_decision_tree

I've figured out the basic ways of specifying attributes in R, (e.g. 
V(g)$shape <- "rectangle"); however there are a few things that I can't 
seem to figure out.

  * I'm plotting the graph using the layout.reingold.tilford layout.
    However, I wanted to have the root at the top instead of the bottom.
    Is there an easy way to specify this or do I need to dig into the code
    and create an option?

  * I'm use larger labels than are normally used with the package.  As
    such, I'm attempting to set the size of the node appropriately, since
    it is not automatically resized for the given text.  I'm currently
    using a few hacks, but nothing serious.  Does anyone have any
    suggestions for robustly resizing vertices to be compatible with
    arbitrary text?

  * I noticed that plotting a large tree using the postscript device in R
    gives a fairly difficult to read output (e.g plot(graph.tree(1000, 2)))
    Is there an easy way to resize the page so that the tree can be more
    spread out?

Any advise is greatly appreciated!

Thanks,

Aaron