nx.write_dot(...) generates redundant nodes when input nodes have a colon

Question

import networkx as nx

G = nx.DiGraph()
G.add_edge("A: test", 'B: test')

nx.write_dot(G,'so.dot')

Produces

This is due to the colon.

so.dot:

strict digraph G {
A;
B;
"A: test" -> "B: test";
}

Notice it strips the colon and everything behind it.

If I manually change this to

strict digraph G {
"A: test";
"B: test";
"A: test" -> "B: test";
}

it's fine. In fact it doesn't matter if there are nodes, as long as there are edges.

If I remove the space between : and t, only A and B are generated.

I've tried escaping the colon in various ways, but that doesn't seem to work. I can manually delete the nodes every time, obviously, but a scripted solution would be preferable. (And not a second script that goes through the .dot file)

Anyone have an idea?

Answer 1

This isn't a bug, it's a feature of the GraphViz Dot language syntax. The colon in a node name is used to specify input or output ports.

From the GraphViz docs, Node, Edge and Graph Attributes

portPos

Modifier indicating where on a node an edge should be aimed. It has the form portname(:compass_point)? or compass_point. If the first form is used, the corresponding node must either have record shape with one of its fields having the given portname, or have an HTML-like label, one of whose components has a PORT attribute set to portname.

However, according to this answer you can over-ride this behaviour by passing Graphviz a quoted node name, eg,

G.add_edge("'A: test'", "'B: test'")