Family tree layout with Dot/GraphViz

Question

I am trying to draw a family tree with Dot and GraphViz.

This is what I currently have:

# just graph set-up
digraph simpsons {
ratio = \"auto\"
minc         


        

Answer 1

Although you can't control node placement, I found you can help node placement by ordering the nodes in a different order. I re-ordered some of the nodes as shown below and got a graph that produced no cross-overs.

The following code:

digraph G {
  edge [dir=none];
  node [shape=box];

  "Herb"      [shape=box, regular=1, color="blue"] ;
  "Homer"     [shape=box, regular=1, color="blue"] ;
  "Marge"     [shape=box, regular=1, color="pink"] ;
  "Clancy"    [shape=box, regular=1, color="blue"] ;
  "Jackeline" [shape=box, regular=1, color="pink"] ;
  "Abraham"   [shape=box, regular=1, color="blue"] ;
  "Mona"      [shape=box, regular=1, color="pink"] ;
  "Patty"     [shape=box, regular=1, color="pink"] ;
  "Selma"     [shape=box, regular=1, color="pink"] ;
  "Bart"      [shape=box, regular=1, color="blue"] ;
  "Lisa"      [shape=box, regular=1, color="pink"] ;
  "Maggie"    [shape=box, regular=1, color="pink"] ;
  "Ling"      [shape=box, regular=1, color="blue"] ;

  a1 [shape=circle,label="",height=0.01,width=0.01];
  b1 [shape=circle,label="",height=0.01,width=0.01];
  b2 [shape=circle,label="",height=0.01,width=0.01];
  b3 [shape=circle,label="",height=0.01,width=0.01];
  {rank=same; Abraham -> a1 -> Mona};
  {rank=same; b1 -> b2 -> b3};
  {rank=same; Herb; Homer};
  a1 -> b2
  b1 -> Herb
  b3 -> Homer

  p1 [shape=circle,label="",height=0.01,width=0.01];
  q1 [shape=circle,label="",height=0.01,width=0.01];
  q2 [shape=circle,label="",height=0.01,width=0.01];
  q3 [shape=circle,label="",height=0.01,width=0.01];
  {rank=same; Homer -> p1 -> Marge};
  {rank=same; q1 -> q2 -> q3};
  {rank=same; Bart; Lisa; Maggie};
  p1 -> q2;
  q1 -> Bart;
  q2 -> Lisa;
  q3 -> Maggie;

  x1 [shape=circle,label="",height=0.01,width=0.01];
  y1 [shape=circle,label="",height=0.01,width=0.01];
  y2 [shape=circle,label="",height=0.01,width=0.01];
  y3 [shape=circle,label="",height=0.01,width=0.01];
  {rank=same; Clancy -> x1 -> Jackeline};
  {rank=same; y1 -> y2 -> y3};
  {rank=same; Marge; Patty; Selma};
  {rank=same; Bart; Ling}
  x1 -> y2;
  y1 -> Marge;
  y2 -> Patty;
  y3 -> Selma;
  Selma -> Ling;
}

now produces this:

I don't fully understand why it's working, but here is the thought process into the changes that I made.

1. I placed Clancy/Jackeline before Abraham/Mona thinking that they were on the wrong side. This changed the picture, but still wasn't perfect.
2. I placed Homer/Marge first thinking that the software had to consider these pieces first and maybe place all other nodes relative to Homer/Marge. This further helped, but still wasn't perfect.
3. Herb was still mis-placed, so I put Herb first so that graphviz might consider placement of herb first.

It worked, but I still can't devise an algorithm that would ensure consistent trees with no overlapping edges. I feel that graphviz should do a better job without these hints. I don't know the algorithm used, but if they consider an objective function to minimize or eliminate overlapping edges, it should be possible to devise a better algorithm.