Annotate DOT graphs with images

Question

I'm using PyDot to generate Graphviz/dot graphs in python. I would like to annotate my nodes and edges with images read from files, I've found in the documentation how to put an image as a node, but not how to put an image under a node or even less an edge.

http://www.graphviz.org/doc/info/attrs.html

http://www.graphviz.org/doc/info/shapes.html

http://www.graphviz.org/Documentation/html/shapehowto.html

Does anybody know how to do that?

Answer 1

You can use HTML in the labels for nodes and edges. You can find details here: http://www.graphviz.org/doc/info/shapes.html#html

Basically you can say something

"a" -> "b" [label = <<TABLE><TR><TD><IMG SRC="path/to/picture"/></TD></TR></TABLE>>]

You can add as many rows and columns as you want in the html labels. It's a little more verbose than standard text labels, but you can do a bit more with them.

Answer 2

One method which can work in cases where edges will always be drawn in the same position is to create a PNG with a transparent background and position the icon in the same place that your edge will be drawn, or use the labeldistance/labelangle attributes to move. I'm not familiar with PyDot but using SQL I would create a case to determine whether or not the image is displayed on the node..

Problem with this method is that the graphs which I'm working with are always positioned differently and will never be the same, so in an ideal case I'd like to add the image to the edge label, or under/to the right of the edge label etc. Did you ever manage to find a workaround?