top-down subgraphs, left-right inside subgraphs

Question

I\'d like to have my graph looks like this:

But I can only get this:

Answer 1

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]
}