In Graphviz(dot language ) what i can do for getting nodes horizontal manner. I am using rankdir=LR but when i am using in subgraph it does not work

Question

I am beginner using Graphviz. what can I do for getting like this? Can you guys please help me, Thanks in advance.

Answer 1

Use "same" rank to build columns out of clustered nodes

Use "invisible" arrows to "align" top nodes at each cluster in a row

Use "newrank=true" and "{rank=same ...}" for all top nodes from each first cluster in each row. If you do not do that your graph will fell apart by removing links to a start node.

digraph G {

    rankdir=LR;
    newrank=true;

    subgraph cluster_a {
        subgraph cluster_a0 {
            rank=same;
            a00;a01;a02;a03;
        }
        subgraph cluster_a1 {
            rank=same;
            a10;a11;a12;
        }
    }

    subgraph cluster_b {
        subgraph cluster_b0 {
            rank=same;
            b00;b01;
        }
        subgraph cluster_b1 {
            rank=same;
            b10;b11;b12;b13;
        }
        subgraph cluster_b2 {
            rank=same;
            b20;b21;b22;
        }
    }

    subgraph cluster_c {
        subgraph cluster_c0 {
            rank=same;
            c00;c01;
        }
    }

    first -> second;

    second -> a00;
    second -> b00;
    second -> c00;

    a00 -> a10 [style=invisible, arrowhead=none];
    b00 -> b10 -> b20 [style=invisible, arrowhead=none];

    {rank=same a00 b00 c00}
}