Thanks again,
But I'm talking about edge weights - why would you put in "get(vertex_index,g)" and not "get(edge_index,g)" or similar (I've tried this simple substitution and it doesn't work; so it's obviously more complex than that)?
OK. I misread that -- you do want edge_index. You will need to provide them yourself, though. You must have some mapping from edges to numbers already to index the vector; that needs to be turned into a property map.
Exactly, that's the bit I can't understand. How do I do that? It's not a stupid question, I've been banging my head against it for 2 weeks but the documentation is full of examples far more complex than I need and I lose myself in the syntax (I'm a half-newbie to C++, which is not helping).
I do not know the exact cause of the operator[] error; you removed too much of the error message to tell.
So it's probably due to using "vertex_index" to get edge weights right? In any case, let's see if it still occurs when we figure out the right property_map. If so, then I can paste the entire error (it's very long and, to me, indecipherable). Fergal.