Center last node of a graph

Question

digraph {
  1 -> 2 -> 3;
  2 -> { rank = sink; end};
}

How can I force the "end" node to be centered horizontally (in the same column as the first node)?

Answer 1

You may use the group attribute of the nodes:

digraph {
  3[group=b];
  node[group=a]
  1 -> 2 -> end;
  2 -> 3;
}

See also this and this answer.