Matrix-like layout

[steveroush]

Instead of clusters, this uses rank and the group attributes to align nodes.

• rank=same always (or almost always?) keeps nodes aligned.
• group=xyz usually keeps nodes aligned.
• other changes are just cosmetic.

digraph {
    rankdir=LR
    color=transparent
    node [group="upper"]  // try to keep same Y value
    Start FA FB FC FD  Goal
    node [group="lower"]  // try to keep same Y value
    A B D
    
    { rank=same  // keep same X value
        FA->A [style="invis"]
    }

    { rank=same // keep same X value
        FB->B[style="invis"]
    }

    { rank=same // keep same X value
        FD->D[style="invis"]
    }

    Start -> FA -> FB -> FC -> FD -> Goal
    A -> B -> FD
}