Re: [boost] A very simple question about vertexes (vertices?)

From: Douglas Gregor (gregod_at_[hidden])
Date: 2003-04-16 08:47:06

On Wednesday 16 April 2003 12:18 am, Eric Fowler wrote:
> Sorry if this is obvious, I am just getting started with BGL.
>
> I wish to make a simple geometric graph, in which vertices are comprised of
> points in x, y space(x, y being unsigned integers), and edge weights are
> unsigned integers equal to the distance-squared between the vertex points.
>
> Simple, huh?
>
> Here's where I am at:
>
> #include "stdafx.h"
> #include <boost\config.hpp>
> #include <boost\graph\adjacency_list.hpp>
> using namespace boost;
>
> typedef std::pair<unsigned, unsigned> Point;
> int main(int argc, char* argv[])
> {
> 	typedef adjacency_list<listS, vecS, directedS> Graph;
> 	Graph g;
> 	Point p(1, 2); //just to show it all compiles
> 	return 0;
> }
>
> Now, how do I "tell" my Graph I am storing Point vertices with unsigned int
> edges? Do I need to define properties? How?

You'll need create a name (tag) for the point property:
  struct vertex_location_t { typedef boost::vertex_property_tag kind; };

Then install the property into the vertex:
  typedef adjacency_list<listS, vecS, directedS, 
                                       property<vertex_location_t, Point> >
    Graph;

Similarly, you can install an edge weight property with the predefined name 
boost::edge_weight_t on the edges this way:
  typedef adjacency_list<listS, vecS, directedS,
                                       property<vertex_location_t, Point>,
                                       property<edge_weight_t, unsigned int> >
     Graph;

        HTH,
        Doug