How to get different ranksep for certain ranks

Question

I want my bottom rank of nodes to have smaller ranksep than the rest of my graph. How do you do this? I can't seem to find the right syntax to set ranksep separately for different subgraphs.

This is not working - all ranks are separated the same (both the big ranksep and small ranksep are ignored):

graph G{
  {  ranksep=1.0; // big separation
     1 -- 2
     1 -- 3
  }
  {  ranksep=0.2;  // small separation
     2 -- 4
     2 -- 5
     3 -- 6
     3 -- 7
  }
}

Result:

Dukey

Answer 1

ranksep is an graph attribute (not subgraph), and cannot be used to vary the distance between ranks within the same graph in dot.

Plover

Well that's a bummer. Could this be simulated with invisible nodes? – Dukey

You should be able to add an invisible rank by inserting invisible nodes (a vertical column above node 4 for example). Or you may try adding an invisible node to the same rank and apply some margin (maybe with shape=none, label=" ", margin=1). Or you use gvpr to change the position of the lowest nodes and render the resulting graph with neato. – Plover

Answer 2

You can specifiy a minimum length for an edge. From dotguide : "minlen defines the minimum difference between the ranks of the head and tail". Note that you'll may have to tune both ranksep (global) and minlen to tune the aspect of your graph.

graph G{
  ranksep=0.1;  // small separation
  {  
     1 -- 2 [ minlen =4]
     1 -- 3 [ minlen =4]
  }
  {  
     2 -- 4
     2 -- 5
     3 -- 6
     3 -- 7
  }
}

Result :

Wesleywesleyan