deepcopy of Vertices, Edges and Graphs

Hi,

After processing an external text file I create a an object that among other
things holds a graph object, properties, vertices etc etc.
I would like to save the original copy of the object, so after I can always
refer back to it in a speedy fashion without having to re-parse the text
file and re-initialize the object, but when I tried to use deepcopy() it
complains.
I can not even perform a deep copy on a Vertex object.

Any idea why this is happening, and most importantly is there a work around?
(I tried pickle and shelve and they do not work either).

Thanks in advance for the response,
Vaggelis

It is difficult to be precise, since you have not given a concrete
example. But the only general issue I can see is that Vertex and Edge
objects are not pickable. You should instead store their integer and
pair representations, respectively:

    v = int(v)
    e = (int(e.source()), int(e.target()))

and pickle that.

Best,
Tiago