How to parse a DOT file in Python

Question

I have a transducer saved in the form of a DOT file. I can see a graphical representation of the graphs using gvedit, but what if I want to convert the DOT file to an executable transducer, so that I can test the transducer and see what strings it accepts and what it doesn't.

In most of the tools I have seen in Openfst, Graphviz, and their Python extensions, DOT files are only used to create a graphical representation, but what if I want to parse the file to get an interactive program where I can test the strings against the transducer?

Are there any libraries out there that would do the task or should I just write it from scratch?

As I said, the DOT file is related to a transducer I have designed that simulates morphology of English. It is a huge file, but just to give you an idea of how it is like, I provide a sample. Let's say I want to create a transducer that would model the behavior of English with regards to Nouns and in terms of plurality. My lexicon consists of only three words (book, boy, girl). My transducer in this case would look something like this:

which is directly constructed from this DOT file:

digraph A {
rankdir = LR;
node [shape=circle,style=filled] 0
node [shape=circle,style=filled] 1
node [shape=circle,style=filled] 2
node [shape=circle,style=filled] 3
node [shape=circle,style=filled] 4
node [shape=circle,style=filled] 5
node [shape=circle,style=filled] 6
node [shape=circle,style=filled] 7
node [shape=circle,style=filled] 8
node [shape=circle,style=filled] 9
node [shape=doublecircle,style=filled] 10
0 -> 4 [label="g "];
0 -> 1 [label="b "];
1 -> 2 [label="o "];
2 -> 7 [label="y "];
2 -> 3 [label="o "];
3 -> 7 [label="k "];
4 -> 5 [label="i "];
5 -> 6 [label="r "];
6 -> 7 [label="l "];
7 -> 9 [label="<+N:s> "];
7 -> 8 [label="<+N:0> "];
8 -> 10 [label="<+Sg:0> "];
9 -> 10 [label="<+Pl:0> "];
}

Now testing this transducer against the words means that if you feed it with book+Pl it should spit back books and vice versa. I'd like to see how it is possible to turn the dot file into a format that would allow such analysis and testing.

Answer 1

Another path, and a simple way of finding cycles in a dot file:

import pygraphviz as pgv
import networkx as nx

gv = pgv.AGraph('my.dot', strict=False, directed=True)
G = nx.DiGraph(gv)

cycles = nx.simple_cycles(G)
for cycle in cycles:
    print(cycle)

Answer 2

Use this to load a .dot file in python:

graph = pydot.graph_from_dot_file(apath)

# SHOW as an image
import tempfile, Image
fout = tempfile.NamedTemporaryFile(suffix=".png")
graph.write(fout.name,format="png")
Image.open(fout.name).show()