Re: [Boost-users] Boost-users Digest, Vol 2928, Issue 3

7 Dec 2011

      On Wed, 7 Dec 2011, Nicolas Saunier wrote:
...
Hi,
On 11-12-07 02:21 PM, boost-users-request@lists.boost.org wrote:
...
Message: 6
Date: Wed, 7 Dec 2011 14:19:46 -0500 (EST)
From: Jeremiah Willcock
To:boost-users@lists.boost.org
Subject: Re: [Boost-users] [BGL] Issue using connected_components
Message-ID:
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
On Wed, 7 Dec 2011, Nicolas Saunier wrote:
...
...
Hi,
here is a simplified code sample that I cannot get to work. I use 
bundled
 properties for an undirected graph and I do not find what should be the 
type
 of the component map (or property map) that should be passed as the 
second
 argument of the connected_components function. The sample is useless 
since
 only integers are for vertices.
The normal vector_property_map class does not work for adjacency_list
graphs with a listS vertex container unless you define a vertex_index_map.
Is there a reason you can't use vecS as the vertex container in your
graph?  If you truly need listS, you will need to create a vertex index
map, fill it in before you create the property map, and pass it to the
vector_property_map constructor (and as a type argument to that class).
-- Jeremiah Willcock
Thanks for replying. The problem, and that may seem too simple or silly to 
people familiar with the library, is that I have no idea what should be the 
type of the component map to pass. I tried to declare the components variable 
as:
vector< graph_traits<FeatureGraph>::vertices_size_type > 
components(num_vertices(g));
And it does not work either. What is the type of the component map, the 
second argument of connected_components? Can you give me an example of a type 
that would work (compile and return the correct results)?
Try:

shared_array_property_map<
   ...::vertices_size_type,
   property_map::const_type
...
components(num_vertices(g), get(vertex_index, g));

This requires a vecS vertex container, though.

-- Jeremiah Willcock