Re: [Boost-users] BGL: copy graph & edge predicate question

From: Douglas Gregor (doug.gregor_at_[hidden])
Date: 2005-05-18 21:18:30

On Apr 28, 2005, at 5:39 AM, Sebastian Weber wrote:

> Hello Everybody!
>
> I am trying to extract a part of a graph. Speaking in terms of the BGL,
> I do a copy from a filtered graph object into a new graph. To do so, I
> defined a VerticePredicate for the filtered graph. As a result not all
> vertices in the graph are present in the filtered version. This implies
> that some edges do disappear in the filtered version fo the graph. In
> order to copy from this filtered graph into a new, fresh graph via 
> copy,
> do I have to use the following EdgePredicate?
[snip predicate that also checks vertex]
 > Or is this not necessary and implicitly done by the filtered graph
> interface?

The filtered graph already does this for you.

> Another thing concernig the copy-function: Is there a way to NOT copy
> the vertice indices, but rather have the vertices renumbered from 1 to
> size of filtered graph? I guess I have to cope with the
> vertice_copier-function stuff, but I don't see how to do it.

If you are referring to copying the vertex_index property, you're 
probably better off just renumbering vertices at the end.

> And another matter: The copy_component function does not seem to be
> documented. I found it by chance in the sources of copy.hpp.

I've never even heard of this function :) It does look useful... adding 
it to the list o' bugs, and we'll try to get to it soon.

        Doug