Issue attachments for pydot/pydot-ng#80: https://github.com/pydot/pydot-ng/issues/80

pydot_bug.py

import pydot

g = pydot.graph_from_dot_data("digraph G {1 -> 2;}")
print("Simple DOT:\n{0}".format(g.to_string()))
print("Nodes: {0}, edges: {1}".format(len(g.get_nodes()), len(g.get_edges())))
g.write_png("simple.png")

g.set_node_defaults(style="filled", fillcolor="yellow")
print("DOT with yellow fill (wrong):\n{0}".format(g.to_string()))
g.write_png("simple.yellow.png")

g = pydot.graph_from_dot_data("""
digraph G {
    node [style=filled, fillcolor=yellow];
    1 -> 2;
}
""")
print("DOT with yellow fill (good):\n{0}".format(g.to_string()))
g.write_png("simple.good.png")