Align nodes in a Graphviz directed graph - graphviz

Question

I have the following Graphviz code:
digraph {
Technique [shape = box];
Path [shape = box];
KnowledgeObservation [shape = box, label = "Knowledge\nObservation"];
ManagementIntervention [shape = box, label = "Management\nIntervention"];
ResultsModification [shape = box, label = "Results\nModification"];
SharedCode [label = "Shared Code"];
MediatedRelationship [label = "Mediated Relationship"];
Art -> Technique;
Therapy -> Path;
{Technique Path} -> KnowledgeObservation -> ManagementIntervention -> ResultsModification;
{MediatedRelationship SharedCode} -> {KnowledgeObservation ResultsModification}
subgraph {
rank = same
Technique -> Path [dir = none]
}
subgraph {
rank = same
SharedCode
ManagementIntervention
MediatedRelationship
}
}
It currently produces the following output:
How can I vertically align "Management Intervention" with both "Knowledge Observation" and "Results Modification"?
"Shared Code" should be moved to the left of "Management Intervention".
"Mediated Relationship" should be moved to the right of "Management Intervention".
"Shared Code", "Management Intervention" and "Mediated Relationship" should stay horizontally aligned.
How can I accomplish this?

Answer 1

This can be achieved without subgraphs; the most important modification is the line
{ rank = same; SharedCode -> ManagementIntervention -> MediatedRelationship[ style = invis ] }
which keeps the three nodes not only on the right level, but also within the desired order.
Altogether, this code here
digraph
{
// node definition
Art Therapy;
Technique[ shape = box ];
Path[ shape = box ];
KnowledgeObservation[ shape = box, label = "Knowledge\nObservation" ];
ManagementIntervention[ shape = box, label = "Management\nIntervention" ];
ResultsModification[ shape = box, label = "Results\nModification" ];
SharedCode[ label = "Shared Code" ];
MediatedRelationship[ label = "Mediated Relationship" ];
// edges
Art -> Technique;
Therapy -> Path;
{ rank = same; Technique -> Path [dir = none] }
{ Technique Path} -> KnowledgeObservation -> ManagementIntervention -> ResultsModification;
{ rank = same; SharedCode -> ManagementIntervention -> MediatedRelationship[ style = invis ] }
{ MediatedRelationship SharedCode } -> { KnowledgeObservation ResultsModification }
}
gives you
which is, in my understanding, what you are looking for.
Still I would recommend to replace the last line of code with these three
KnowledgeObservation -> { SharedCode MediatedRelationship }[ dir = back ];
SharedCode -> ResultsModification;
MediatedRelationship -> ResultsModification;
Reason is that once your graph gets more complicated, graphviz will recognize and maintain the hierarchical relationships, rather than interpreting ambiguous instructions in surprising ways.

Answer 2

How can I vertically align "Management Intervention" with both "Knowledge Observation" and "Results Modification"?
This can be achieved with increasing the weight of the edge. Edges with higher weight tend to be straighter and shorter than with the lower.
"Mediated Relationship" should be moved to the right of "Management Intervention".
You can control this with the order in which the nodes are defined. If you define "Management Intervention" before the "Shared Code", it (MI) will be drawn first, i. e., to the left of the SI.
"Shared Code", "Management Intervention" and "Mediated Relationship" should stay horizontally aligned.
You did it right, using the rank=same subgraph attribute. Though I would put the subgraph already in the moment of node definitions. This will shorten the source size and limit the rank specification to the place where the nodes are defined, which is good for readability (everything stated in one place).
Your modified example:
digraph {
Technique [shape = box];
Path [shape = box];
KnowledgeObservation [shape = box, label = "Knowledge\nObservation"];
ResultsModification [shape = box, label = "Results\nModification"];
subgraph {
rank=same
ManagementIntervention [shape = box, label = "Management\nIntervention"];
MediatedRelationship [label = "Mediated Relationship"];
SharedCode [label = "Shared Code"];
}
Art -> Technique;
Therapy -> Path;
{Technique Path} -> KnowledgeObservation
KnowledgeObservation -> ManagementIntervention -> ResultsModification [weight=3]
{MediatedRelationship SharedCode} -> {KnowledgeObservation ResultsModification}
subgraph {
rank = same
Technique -> Path [dir = none]
}
}
Result: