Graphviz .dot node ordering

Question

I'm building a epsilon NFA to recognize a regular expression using the canonical construction. I'm using subgraphs to group various parts of the regular expression. The * operator is giving me particular trouble since dot has decided to move the order of the nodes around. I've tried adding edge weights to force particular edges to be short to keep the order of the edges in line but that does not seem to be working.

What I would like to do is force the nodes in a subgraph in to be placed in a particular order so that the output graph is recognizable as a particular type of (well known) construction. In the example below I would like edges 3, 4, 5 and 6 placed in that order, however the dot places them in the order 6, 3, 4, 5. Any pointers appreciated.

Note that the current weight parameter produces no difference than no weight parameter at all.

I have the following

digraph G {     rankdir = LR;     node [shape = none];             0 [label = "start"];     node [shape = circle];             1 [label = "q1"];             2 [label = "q2"];             3 [label = "q3"];             4 [label = "q4"];             5 [label = "q5"];     node [shape = doublecircle];             6 [label = "q6"];     subgraph re1 {             rank = same;             edge[label = "0"];             1 -> 2;     };     subgraph re2 {             rank = same;             edge[label = "ε"];                     3 -> 4 [weight = 10];             edge[label = "1"];                     4 -> 5 [weight = 10];             edge[label = "ε"];                     5 -> 6 [weight = 10];                     5 -> 4 [weight = 1];                     6 -> 3 [weight = 1];     };     edge[color=black];             0 -> 1     edge[label = "ε"];             2 -> 3; } 

Answer 1

Here's how I'd write that graph:

• First of all, to me this is a graph which goes from top to bottom, not left to right, therefore I removed the rankdir=LR and added rank=same only for nodes 0/1 and nodes 2/3.
• I removed all the weights
• Most importantly, I added constraint=false to the edges going against the direction of the graph - the one going from node 4 to node 5, and the one from node 6 to node 3.

Here the source:

digraph G {     0 [label = "start", shape = none];      node [shape = circle];     1 [label = "q1"];     2 [label = "q2"];     3 [label = "q3"];     4 [label = "q4"];     5 [label = "q5"];     6 [label = "q6", shape = doublecircle];      {rank = same; 0 -> 1; }     1 -> 2 [label = "0"];     {rank = same; 2 -> 3 [label = "ε"]; }     4 -> 5 [label = "1"];     edge [label = "ε"];     3 -> 4;     5 -> 6;     5 -> 4 [constraint = false];     6 -> 3 [constraint = false]; } 

And here's the result:

Now if you want to, you could keep rankdir=LR, just take the markup you posted, remove the weights and add constraint=false to the same edges as I did, it works, too.