Graphviz: Is there a way to force a node to the bottom?

Question

I'm building a CFG (Context-free grammar), and I'd like the exit node to always be at the bottom of the graph. Sometimes it happens naturally, sometimes it doesn't.

Example:

digraph G {
  0;
  1;
  4;
  5;
  7;
  8;
  0 -> 4;
  5 -> 7;
  7 -> 8;
  7 -> 1;
  8 -> 5;
  4 -> 7;
}

Draws (using dot):

Node 1 is my exit node, I'd like that to be at the bottom. Suggestions?

Answer 1

Use rank specification for the subgraph. In this case sink should make it at the bottom and max will make it on the same level as 5:

digraph G {
  0;
  { rank = sink; 1; }
  5;
  4;
  7;
  8;
  0 -> 4;
  5 -> 7;
  7 -> 8;
  7 -> 1;
  8 -> 5;
  4 -> 7;
}