public void CheckPredecessorLineGraph()
{
AdjacencyGraph <int, Edge <int> > g = new AdjacencyGraph <int, Edge <int> >(true);
g.AddVertex(1);
g.AddVertex(2);
g.AddVertex(3);
Edge <int> e12 = new Edge <int>(1, 2); g.AddEdge(e12);
Edge <int> e23 = new Edge <int>(2, 3); g.AddEdge(e23);
Dictionary <Edge <int>, double> weights =
DijkstraShortestPathAlgorithm <int, Edge <int> > .UnaryWeightsFromEdgeList(g);
DijkstraShortestPathAlgorithm <int, Edge <int> > dij = new DijkstraShortestPathAlgorithm <int, Edge <int> >(g, weights);
VertexPredecessorRecorderObserver <int, Edge <int> > vis = new VertexPredecessorRecorderObserver <int, Edge <int> >();
vis.Attach(dij);
dij.Compute(1);
IList <Edge <int> > col = vis.Path(2);
Assert.AreEqual(1, col.Count);
Assert.AreEqual(e12, col[0]);
col = vis.Path(3);
Assert.AreEqual(2, col.Count);
Assert.AreEqual(e12, col[0]);
Assert.AreEqual(e23, col[1]);
}
public void CheckPredecessorLineGraph()
{
AdjacencyGraph<int, Edge<int>> g = new AdjacencyGraph<int, Edge<int>>(true);
g.AddVertex(1);
g.AddVertex(2);
g.AddVertex(3);
Edge<int> e12 = new Edge<int>(1, 2); g.AddEdge(e12);
Edge<int> e23 = new Edge<int>(2, 3); g.AddEdge(e23);
Dictionary<Edge<int>, double> weights =
DijkstraShortestPathAlgorithm<int, Edge<int>>.UnaryWeightsFromEdgeList(g);
DijkstraShortestPathAlgorithm<int, Edge<int>> dij = new DijkstraShortestPathAlgorithm<int, Edge<int>>(g, weights);
VertexPredecessorRecorderObserver<int, Edge<int>> vis = new VertexPredecessorRecorderObserver<int, Edge<int>>();
vis.Attach(dij);
dij.Compute(1);
IList<Edge<int>> col = vis.Path(2);
Assert.AreEqual(1, col.Count);
Assert.AreEqual(e12, col[0]);
col = vis.Path(3);
Assert.AreEqual(2, col.Count);
Assert.AreEqual(e12, col[0]);
Assert.AreEqual(e23, col[1]);
}
/// <summary>
/// Computes a set of eulerian trail, starting at <paramref name="s"/>
/// that spans the entire graph.
/// </summary>
/// <remarks>
/// <para>
/// This method computes a set of eulerian trail starting at <paramref name="s"/>
/// that spans the entire graph.The algorithm outline is as follows:
/// </para>
/// <para>
/// The algorithms iterates throught the Eulerian circuit of the augmented
/// graph (the augmented graph is the graph with additional edges to make
/// the number of odd vertices even).
/// </para>
/// <para>
/// If the current edge is not temporary, it is added to the current trail.
/// </para>
/// <para>
/// If the current edge is temporary, the current trail is finished and
/// added to the trail collection. The shortest path between the
/// start vertex <paramref name="s"/> and the target vertex of the
/// temporary edge is then used to start the new trail. This shortest
/// path is computed using the <see cref="BreadthFirstSearchAlgorithm"/>.
/// </para>
/// </remarks>
/// <param name="s">start vertex</param>
/// <returns>eulerian trail set, all starting at s</returns>
/// <exception cref="ArgumentNullException">s is a null reference.</exception>
/// <exception cref="Exception">Eulerian trail not computed yet.</exception>
public ICollection <ICollection <TEdge> > Trails(TVertex s)
{
if (s == null)
{
throw new ArgumentNullException("s");
}
if (this.Circuit.Count == 0)
{
throw new Exception("Circuit is empty");
}
// find the first edge in the circuit.
int i = 0;
for (i = 0; i < this.Circuit.Count; ++i)
{
TEdge e = this.Circuit[i];
if (this.temporaryEdges.Contains(e))
{
continue;
}
if (e.Source.Equals(s))
{
break;
}
}
if (i == this.Circuit.Count)
{
throw new Exception("Did not find vertex in eulerian trail?");
}
// create collections
List <ICollection <TEdge> > trails = new List <ICollection <TEdge> >();
List <TEdge> trail = new List <TEdge>();
BreadthFirstSearchAlgorithm <TVertex, TEdge> bfs =
new BreadthFirstSearchAlgorithm <TVertex, TEdge>(VisitedGraph);
VertexPredecessorRecorderObserver <TVertex, TEdge> vis =
new VertexPredecessorRecorderObserver <TVertex, TEdge>();
vis.Attach(bfs);
bfs.Compute(s);
// go throught the edges and build the predecessor table.
int start = i;
for (; i < this.Circuit.Count; ++i)
{
TEdge e = this.Circuit[i];
if (this.temporaryEdges.Contains(e))
{
// store previous trail and start new one.
if (trail.Count != 0)
{
trails.Add(trail);
}
// start new trail
// take the shortest path from the start vertex to
// the target vertex
trail = vis.Path(e.Target);
}
else
{
trail.Add(e);
}
}
// starting again on the circuit
for (i = 0; i < start; ++i)
{
TEdge e = this.Circuit[i];
if (this.temporaryEdges.Contains(e))
{
// store previous trail and start new one.
if (trail.Count != 0)
{
trails.Add(trail);
}
// start new trail
// take the shortest path from the start vertex to
// the target vertex
trail = vis.Path(e.Target);
}
else
{
trail.Add(e);
}
}
// adding the last element
if (trail.Count != 0)
{
trails.Add(trail);
}
return(trails);
}
/// <summary>
/// Carries out the shortest path between the two nodes
/// ids passed as variables and returns an <see cref="ILineString" />
/// giveing the shortest path.
/// </summary>
/// <param name="source">The source node</param>
/// <param name="destination">The destination node</param>
/// <returns>A line string geometric shape of the path</returns>
public ILineString Perform(ICoordinate source, ICoordinate destination)
{
if (!graph.ContainsVertex(source))
throw new ArgumentException("key not found in the graph", "source");
if (!graph.ContainsVertex(destination))
throw new ArgumentException("key not found in the graph", "destination");
// Build algorithm
DijkstraShortestPathAlgorithm<ICoordinate, IEdge<ICoordinate>> dijkstra =
new DijkstraShortestPathAlgorithm<ICoordinate, IEdge<ICoordinate>>(graph, consts);
// Attach a Distance observer to give us the distances between edges
VertexDistanceRecorderObserver<ICoordinate, IEdge<ICoordinate>> distanceObserver =
new VertexDistanceRecorderObserver<ICoordinate, IEdge<ICoordinate>>();
distanceObserver.Attach(dijkstra);
// Attach a Vertex Predecessor Recorder Observer to give us the paths
VertexPredecessorRecorderObserver<ICoordinate, IEdge<ICoordinate>> predecessorObserver =
new VertexPredecessorRecorderObserver<ICoordinate, IEdge<ICoordinate>>();
predecessorObserver.Attach(dijkstra);
// Run the algorithm with A set to be the source
dijkstra.Compute(source);
// Get the path computed to the destination.
IList<IEdge<ICoordinate>> path = predecessorObserver.Path(destination);
// Then we need to turn that into a geomery.
if (path.Count > 1)
return buildString(path);
// if the count is greater than one then a
// path could not be found, so we return null
return null;
}