Making an edge between a node and a subgraph

[veberle]

Making an edge between a note and a subgraph doesn't seem to work. Instead a new node is generated with the name of the subgraph.

c0 = g.add_graph( "cluster0", "label" => "cluster #1"  )
a0 = c0.add_nodes( "a0" )

c1 = g.add_graph( "cluster1", "label" => "cluster #2" )
b0 = c1.add_nodes( "b0" )

g.add_edges(c0,c1)
g.add_edges(c0,b0)

is generated to

digraph G {
subgraph cluster0 {
  label = "cluster #1";
  a0 [label = "a0"];
}
subgraph cluster1 {
  label = "cluster #2";
  b0 [label = "b0"];
}
  cluster0 [label = "cluster0"];
  cluster1 [label = "cluster1"];
  cluster0 -> cluster1
  cluster0 -> b0
}

I was trying something like this

[glejeune]

If you try the fdpcplus example (http://www.graphviz.org/Gallery/undirected/fdpclust.html) you will see that it does not work either. As indicated on the example's page, "fdp is being actively worked on, so the probability of hitting a bug is higher than with neato". I think, this is a fdp bug. I'll ask on the graphviz mailing list.

[glejeune]

Hi,

In the meantime, you can use "compound", "lhead" and "ltail" attributes, to clip the edge to the boundary of a cluster. Here is an example :

g = GraphViz::new( "G", :type => "graph" )
g[:compound] = true
g[:rankdir] = "LR"

c0 = g.add_graph( "cluster0", "label" => "cluster #1"  )
a0 = c0.add_nodes( "a0" )

c1 = g.add_graph( "cluster1", "label" => "cluster #2" )
b0 = c1.add_nodes( "b0" )

e1 = g.add_edges(a0,b0)
e1[:lhead] = c1.id
e1[:ltail] = c0.id

e2 = g.add_edges(a0,b0)
e2[:lhead] = c1.id

For more informations about these attributs, see http://www.graphviz.org/content/attrs

[glejeune]

That has been confirmed, it is a bug in graphviz 2.28.