top-down subgraphs, left-right inside subgraphs - graphviz

Question

I'd like to have my graph looks like this:
But I can only get this:
The problem is, rankdir does not work in subgraph.
So, how to emulate it?
The code:
digraph G {
node [shape = circle]
0 [style = invis]
0 -> "0A"
subgraph clusterA {
label=A
"0A"
"1A"
"2A" -> "0A" [label=•]
}
subgraph clusterB {
label=B
"0B"
"1B"
"2B" -> "0B" [label=•]
}
subgraph clusterC {
label=C
"0C"
"1C"
"2C" -> "0C" [label=•]
}
subgraph clusterD {
label=D
"0D"
"1D"
"2D" -> "0D" [label=•]
}
subgraph clusterE {
label=E
"0E"
"1E"
"2E" -> "0E" [label=•]
}
subgraph clusterF {
label=F
{node [shape = doublecircle] "0F" "1F"}
"2F" -> "0F" [label=•]
}
"0A" -> "1B" [label=a]
"1A" -> "2B" [label=a]
"0B" -> "1C" [label=b]
"1B" -> "2C" [label=b]
"0C" -> "1D" [label=c]
"1C" -> "2D" [label=c]
"0D" -> "1E" [label=d]
"1D" -> "2E" [label=d]
"0E" -> "1F" [label=e]
"1E" -> "2F" [label=e]
}

Answer 1

Reproducing particular graph layouts usually can be achieved with:
Invisible nodes and edges
rank constraints
Here's how I reproduced your graph - or at least a part of it:
digraph g {
rankdir="LR";
node[shape = circle, fontsize=14];
fontsize=18;
labeljust="l";
edge[style=invis, fontsize=12];
{ rank=same;
0 [style = invis];
01 [style = invis];
02 [style=invis];
0 -> 01 -> 02;
}
subgraph clusterA {
"0A" -> "1A" -> "2A";
"2A" -> "0A" [label=".", constraint=false, style=solid];
label="A";
}
subgraph clusterB {
"0B" -> "1B" -> "2B";
"2B" -> "0B" [label=".", constraint=false, style=solid];
label="B";
}
subgraph clusterC {
"0C" -> "1C" -> "2C";
"2C" -> "0C" [label=".", constraint=false, style=solid];
label="C";
}
0 -> "0A"[style=solid];
01 -> "0B"[style=invis];
02 -> "0C"[style=invis];
// edges between clusters
edge[constraint=false, style=solid];
"0A" -> "1B" [label=a]
"1A" -> "2B" [label=a]
"0B" -> "1C" [label=b]
"1B" -> "2C" [label=b]
}
This solution is not very intuitive. A couple of points to achieve this:
I chose rankdir="LR" which resulted in nicer edges than TB, though it does not really correspond with the direction of the graph
Invisible nodes and edges are use for the top rank nodes (0, 01, 02) in order to have the clusters align left.
The (invisible) top nodes are forced to the same rank and are linked by invisible edges - this will ensure that the clusters linked to each node appear in the correct order.
The result is:

Answer 2

It looks like rank=same might be a cleaner solution. Take a look at Placing clusters on the same rank in Graphviz.
You can also use 'constraint=false' and invisible edges to carefully control node rank. This is basically the same answer as the above.
digraph G {
newrank=true; // rank without respect to cluster
rankdir="LR";
node [shape = circle]
subgraph clusterA {
a0 -> a1 -> a2 [style = invis] // set node order in cluster
a2 -> a0 [constraint=false] //don't use this edge for ranking
}
subgraph clusterB {
b0 -> b1 -> b2 [style = invis]
b2 -> b0 [constraint=false]
}
a0 -> b1 [constraint=false]
a1 -> b2 [constraint=false]
}

Answer 3

Using constraint=false should get the nodes in your subgraphs to turn out the way you want
http://www.graphviz.org/doc/info/attrs.html#d:constraint
subgraph clusterB {
label=B
"0B"
"1B"
"2B" -> "0B" [constraint=false label=•]
}
After that you'll find that your subgraphs don't line up with each other the way you want. Something like this could resolve that.
"0A" -> "0B" -> "0C" -> "0D" -> "0E" [weight=999 style=invis];

Answer 4

An update on #marapet's answer using group
digraph g {
rankdir="LR";
node[shape = circle, fontsize=14];
fontsize=18;
labeljust="l";
edge[style=invis, fontsize=12];
{ rank=same;
0 [group=a style = invis];
01 [style = invis];
02 [group=b style=invis];
0 -> 01 -> 02;
}
subgraph clusterA {
"0A" [group=a]
"0A" -> "1A" -> "2A";
"2A" -> "0A" [label=".", constraint=false, style=solid];
label="A";
}
subgraph clusterB {
"0B" -> "1B" -> "2B";
"2B" -> "0B" [label=".", constraint=false, style=solid];
label="B";
}
subgraph clusterC {
"0C" [group=b]
"1C" [group=b]
"0C" -> "1C" -> "2C";
"2C" -> "0C" [label=".", constraint=false, style=solid];
label="C";
}
0 -> "0A"[style=solid];
01 -> "0B"[style=invis];
02 -> "0C"[style=invis];
// edges between clusters
edge[constraint=false, style=solid];
"0A" -> "1B" [label=a]
"1A" -> "2B" [label=a]
"0B" -> "1C" [label=b]
"1B" -> "2C" [label=b]
}

Answer 5

rankdir doesn't work directly in the subgraph, but if you add another set of curly braces - whatever that's called - rankdir works. See below. Then, obviously you need more tricks to restore the alignment and ordering you're after.
digraph G {
node [shape = circle]
0 [style = invis]
0 -> "0A"
subgraph clusterA {
label=A
{
rank=same
"0A"
"1A"
"2A" -> "0A" [label=•]
}
}
subgraph clusterB {
label=B
{
rank=same
"0B"
"1B"
"2B" -> "0B" [label=•]
}
}
subgraph clusterC {
label=C
{
rank=same
"0C"
"1C"
"2C" -> "0C" [label=•]
}
}
subgraph clusterD {
label=D
{
rank=same
"0D"
"1D"
"2D" -> "0D" [label=•]
}
}
subgraph clusterE {
label=E
{
rank=same
"0E"
"1E"
"2E" -> "0E" [label=•]
}
}
subgraph clusterF {
label=F
{
rank=same
{node [shape = doublecircle] "0F" "1F"}
"2F" -> "0F" [label=•]
}
}
"0A" -> "1B" [label=a]
"1A" -> "2B" [label=a]
"0B" -> "1C" [label=b]
"1B" -> "2C" [label=b]
"0C" -> "1D" [label=c]
"1C" -> "2D" [label=c]
"0D" -> "1E" [label=d]
"1D" -> "2E" [label=d]
"0E" -> "1F" [label=e]
"1E" -> "2F" [label=e]
}