Color a specific node and its children nodes/edges in one color, and grey everything else out

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2

Others will probably have more elegant suggestions, but I have three ideas:

  1. Render Graphviz graphs directly in your posts discusses some options for animation transitions between different graphs that might be of interest to you.
  2. The Dot input language is designed to be amenable to pre-processing with the C pre-processor, so you could leverage this.
  3. If you’re open to generating your graph from a scripting language, you could do the colourising there.

To expand on (2), you could have something like the following:

digraph {
  A -> B [color=EDGE1];
  B -> C [color=EDGE2];
  C -> D [color=EDGE3];
}

Then you can generate variations of this with:

$ cpp -DEDGE1=black -DEDGE2=black -DEDGE3=red foo.dot # highlight edge 3
$ cpp -DEDGE1=red -DEDGE2=black -DEDGE3=black # highlight edge 1

To expand on (3), you could instead generate the above graph from Python:

import sys

to_highlight = int(sys.argv[1])

edges = [("A", "B"), ("B", "C"), ("C", "D")]

print("digraph {")
for index, (from_node, to_node) in enumerate(1, edges):
  print(f"  {from_node} -> {to_node} "
        f"[color={'red' if index == to_highlight else 'black'}")
printf("}")

Then to do the equivalent of the two cpp scenarios above would be:

$ python3 my_script.py 3
$ python3 my_script.py 1