Re: [Boost-users] BGL: write_graphviz and bundled properties

From: Johan Oudinet (johan.oudinet_at_[hidden])
Date: 2006-04-19 11:46:51

On 4/19/06, Fred Labrosse <ffl_at_[hidden]> wrote:
> All,
>
> First, I'm very new to boost and BGL, so please forgive me if this is trivial.
>
> I've created a graph (adjacency_list) using bundled properties and am now
> trying to write it as a dot file.  I've written my property writer, but when
> I compile, I get several of:
>
> /usr/include/boost/graph/graphviz.hpp: In function `void
> [snip]
> Not being very good at deciphering all that, I'm not sure what is happening.
> I do understand that it's missing an extraction operator but I'm not sure on
> what.  The actual line in graphviz.hpp is:
>
>       out << get(vertex_id, *i);
>
> Two questions:
>
> - Could somebody tell me exactly what that get returns?

get returns the value from vertex_descriptor *i in the property map vertex_id

In your code, your adjacency_list uses listS so this vertex_id
property is not define! That's the problem.

When you call write_graphviz, specify a property map to get an index
from a vertex_descriptor (follow the example with write_graphviz and
dynamic properties)

>
> - From the dot format, this should be the name of the vertex in the dot file.
> So this seems to relate to the class used as a property.  My second question
> is then:  If this is the case, why then do we need the property writer since
> we apparently also need the operator<< that could do exactly the same thing?
> (And isn't a ' ' (space) missing between the vertex name and whatever the
> property writer writes (or should that be included in it, which is not
> mentioned by the documentation)?  That was 3 questions then ;-)

I don't understand your second question, neither question 3... I think
it relates to your first question.

>
> Thanks in advance for any replies.
>
> Cheers,
>

Regards,

--
Johan