/// <summary>
/// Initializes a new instance of the <see cref="FloydWarshallAllShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
public FloydWarshallAllShortestPathAlgorithm(
IVertexAndEdgeListGraph <TVertex, TEdge> visitedGraph,
Func <TEdge, double> edgeWeights,
IDistanceRelaxer distanceRelaxer)
: this(null, visitedGraph, edgeWeights, distanceRelaxer)
{
}
/// <summary>
/// Runs the relaxation algorithm on the given <paramref name="edge"/>.
/// </summary>
/// <param name="edge">Edge to relax.</param>
/// <param name="source">Source vertex.</param>
/// <param name="target">Target vertex.</param>
/// <returns>True if relaxation decreased the target vertex distance, false otherwise.</returns>
protected bool Relax(TEdge edge, TVertex source, TVertex target)
{
Debug.Assert(edge != null);
Debug.Assert(source != null);
Debug.Assert(target != null);
Debug.Assert(
(EqualityComparer <TVertex> .Default.Equals(edge.Source, source) &&
EqualityComparer <TVertex> .Default.Equals(edge.Target, target))
||
(EqualityComparer <TVertex> .Default.Equals(edge.Source, target) &&
EqualityComparer <TVertex> .Default.Equals(edge.Target, source)));
double du = Distances[source];
double dv = Distances[target];
double we = Weights(edge);
IDistanceRelaxer relaxer = DistanceRelaxer;
double duwe = relaxer.Combine(du, we);
if (relaxer.Compare(duwe, dv) < 0)
{
Distances[target] = duwe;
return(true);
}
return(false);
}
private static void CompareSearches <TVertex, TEdge>(
[NotNull] IBidirectionalGraph <TVertex, TEdge> graph,
[NotNull] TVertex root,
[NotNull] TVertex target)
where TEdge : IEdge <TVertex>
{
double EdgeWeights(TEdge edge) => 1.0;
IDistanceRelaxer distanceRelaxer = DistanceRelaxers.ShortestDistance;
var search = new BestFirstFrontierSearchAlgorithm <TVertex, TEdge>(
graph,
EdgeWeights,
distanceRelaxer);
var recorder = new VertexDistanceRecorderObserver <TVertex, TEdge>(EdgeWeights);
using (recorder.Attach(search))
search.Compute(root, target);
var dijkstra = new DijkstraShortestPathAlgorithm <TVertex, TEdge>(graph, EdgeWeights, distanceRelaxer);
var dijkstraRecorder = new VertexDistanceRecorderObserver <TVertex, TEdge>(EdgeWeights);
using (dijkstraRecorder.Attach(dijkstra))
dijkstra.Compute(root);
IDictionary <TVertex, double> bffsVerticesDistances = recorder.Distances;
IDictionary <TVertex, double> dijkstraVerticesDistances = dijkstraRecorder.Distances;
if (dijkstraVerticesDistances.TryGetValue(target, out double cost))
{
Assert.IsTrue(bffsVerticesDistances.ContainsKey(target), $"Target {target} not found, should be {cost}.");
Assert.AreEqual(dijkstraVerticesDistances[target], bffsVerticesDistances[target]);
}
}
/// <summary>
/// Initializes a new instance of the <see cref="BestFirstFrontierSearchAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that for a given edge provide its weight.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
public BestFirstFrontierSearchAlgorithm(
[NotNull] IBidirectionalIncidenceGraph <TVertex, TEdge> visitedGraph,
[NotNull] Func <TEdge, double> edgeWeights,
[NotNull] IDistanceRelaxer distanceRelaxer)
: this(null, visitedGraph, edgeWeights, distanceRelaxer)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="BellmanFordShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
/// <exception cref="T:System.ArgumentNullException"><paramref name="visitedGraph"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="edgeWeights"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="distanceRelaxer"/> is <see langword="null"/>.</exception>
public BellmanFordShortestPathAlgorithm(
[NotNull] IVertexAndEdgeListGraph <TVertex, TEdge> visitedGraph,
[NotNull] Func <TEdge, double> edgeWeights,
[NotNull] IDistanceRelaxer distanceRelaxer)
: this(null, visitedGraph, edgeWeights, distanceRelaxer)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="HoffmanPavleyRankedShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that for a given edge provide its weight.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
/// <exception cref="T:System.ArgumentNullException"><paramref name="visitedGraph"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="edgeWeights"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="distanceRelaxer"/> is <see langword="null"/>.</exception>
public HoffmanPavleyRankedShortestPathAlgorithm(
[NotNull] IBidirectionalGraph <TVertex, TEdge> visitedGraph,
[NotNull] Func <TEdge, double> edgeWeights,
[NotNull] IDistanceRelaxer distanceRelaxer)
: this(null, visitedGraph, edgeWeights, distanceRelaxer)
{
}
private static void RunSearch <TVertex, TEdge>(
[NotNull] IBidirectionalGraph <TVertex, TEdge> graph)
where TEdge : IEdge <TVertex>
{
if (graph.VertexCount == 0)
{
return;
}
IDistanceRelaxer distanceRelaxer = DistanceRelaxers.ShortestDistance;
var search = new BestFirstFrontierSearchAlgorithm <TVertex, TEdge>(
graph,
e => 1,
distanceRelaxer);
TVertex root = graph.Vertices.First();
TVertex target = graph.Vertices.Last();
var recorder = new VertexPredecessorRecorderObserver <TVertex, TEdge>();
using (recorder.Attach(search))
search.Compute(root, target);
if (recorder.VertexPredecessors.ContainsKey(target))
{
Assert.IsTrue(recorder.TryGetPath(target, out _));
}
}
/// <summary>
/// Initializes a new instance of the <see cref="UndirectedDijkstraShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
public UndirectedDijkstraShortestPathAlgorithm(
IUndirectedGraph <TVertex, TEdge> visitedGraph,
Func <TEdge, double> edgeWeights,
IDistanceRelaxer distanceRelaxer)
: this(null, visitedGraph, edgeWeights, distanceRelaxer)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="DagShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
public DagShortestPathAlgorithm(
IVertexListGraph <TVertex, TEdge> visitedGraph,
Func <TEdge, double> edgeWeights,
IDistanceRelaxer distanceRelaxer)
: this(null, visitedGraph, edgeWeights, distanceRelaxer)
{
}
public BellmanFordShortestPathAlgorithm(
IVertexAndEdgeListGraph <TVertex, TEdge> visitedGraph,
Func <TEdge, double> weights,
IDistanceRelaxer distanceRelaxer
)
: this(null, visitedGraph, weights, distanceRelaxer)
{
}
public DagShortestPathAlgorithm(
IVertexListGraph <TVertex, TEdge> g,
IDictionary <TEdge, double> weights,
IDistanceRelaxer distanceRelaxer
)
: base(g, weights, distanceRelaxer)
{
}
public DijkstraShortestPathAlgorithm(
IVertexListGraph <TVertex, TEdge> visitedGraph,
IDictionary <TEdge, double> weights,
IDistanceRelaxer distanceRelaxer
)
: base(visitedGraph, weights, distanceRelaxer)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="UndirectedDijkstraShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="host">Host to use if set, otherwise use this reference.</param>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
public UndirectedDijkstraShortestPathAlgorithm(
IAlgorithmComponent host,
IUndirectedGraph <TVertex, TEdge> visitedGraph,
Func <TEdge, double> edgeWeights,
IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph, edgeWeights, distanceRelaxer)
{
}
public DagShortestPathAlgorithm(
IVertexListGraph <TVertex, TEdge> g,
Func <TEdge, double> weights,
IDistanceRelaxer distanceRelaxer
)
: this(null, g, weights, distanceRelaxer)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="AStarShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="costHeuristic">Function that computes a cost for a given vertex.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
/// <exception cref="T:System.ArgumentNullException"><paramref name="visitedGraph"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="edgeWeights"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="costHeuristic"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="distanceRelaxer"/> is <see langword="null"/>.</exception>
public AStarShortestPathAlgorithm(
[NotNull] IVertexListGraph <TVertex, TEdge> visitedGraph,
[NotNull] Func <TEdge, double> edgeWeights,
[NotNull] Func <TVertex, double> costHeuristic,
[NotNull] IDistanceRelaxer distanceRelaxer)
: this(null, visitedGraph, edgeWeights, costHeuristic, distanceRelaxer)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="DagShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="host">Host to use if set, otherwise use this reference.</param>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
public DagShortestPathAlgorithm(
IAlgorithmComponent host,
IVertexListGraph <TVertex, TEdge> visitedGraph,
Func <TEdge, double> edgeWeights,
IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph, edgeWeights, distanceRelaxer)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="BellmanFordShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="host">Host to use if set, otherwise use this reference.</param>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
/// <exception cref="T:System.ArgumentNullException"><paramref name="visitedGraph"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="edgeWeights"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="distanceRelaxer"/> is <see langword="null"/>.</exception>
public BellmanFordShortestPathAlgorithm(
[CanBeNull] IAlgorithmComponent host,
[NotNull] IVertexAndEdgeListGraph <TVertex, TEdge> visitedGraph,
[NotNull] Func <TEdge, double> edgeWeights,
[NotNull] IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph, edgeWeights, distanceRelaxer)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="RankedShortestPathAlgorithmBase{TVertex,TEdge,TGraph}"/> class.
/// </summary>
/// <param name="host">Host to use if set, otherwise use this reference.</param>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
protected RankedShortestPathAlgorithmBase(
[CanBeNull] IAlgorithmComponent host,
[NotNull] TGraph visitedGraph,
[NotNull] IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph)
{
DistanceRelaxer = distanceRelaxer ?? throw new ArgumentNullException(nameof(distanceRelaxer));
}
public DagShortestPathAlgorithm(
IAlgorithmComponent host,
IVertexListGraph <TVertex, TEdge> g,
Func <TEdge, double> weights,
IDistanceRelaxer distanceRelaxer
)
: base(host, g, weights, distanceRelaxer)
{
}
public AStarShortestPathAlgorithm(
IVertexListGraph <TVertex, TEdge> visitedGraph,
Func <TEdge, double> weights,
Func <TVertex, double> costHeuristic,
IDistanceRelaxer distanceRelaxer
)
: this(null, visitedGraph, weights, costHeuristic, distanceRelaxer)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="HoffmanPavleyRankedShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="host">Host to use if set, otherwise use this reference.</param>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that for a given edge provide its weight.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
/// <exception cref="T:System.ArgumentNullException"><paramref name="visitedGraph"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="edgeWeights"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="distanceRelaxer"/> is <see langword="null"/>.</exception>
public HoffmanPavleyRankedShortestPathAlgorithm(
[CanBeNull] IAlgorithmComponent host,
[NotNull] IBidirectionalGraph <TVertex, TEdge> visitedGraph,
[NotNull] Func <TEdge, double> edgeWeights,
[NotNull] IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph, distanceRelaxer)
{
_edgeWeights = edgeWeights ?? throw new ArgumentNullException(nameof(edgeWeights));
}
/// <summary>
/// Initializes a new instance of the <see cref="VertexDistanceRecorderObserver{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
/// <param name="distances">Distances per vertex.</param>
public VertexDistanceRecorderObserver(
[NotNull] Func <TEdge, double> edgeWeights,
[NotNull] IDistanceRelaxer distanceRelaxer,
[NotNull] IDictionary <TVertex, double> distances)
{
EdgeWeights = edgeWeights ?? throw new ArgumentNullException(nameof(edgeWeights));
DistanceRelaxer = distanceRelaxer ?? throw new ArgumentNullException(nameof(distanceRelaxer));
Distances = distances ?? throw new ArgumentNullException(nameof(distances));
}
/// <summary>
/// Builds a new Bellman Ford searcher.
/// </summary>
/// <param name="g">The graph</param>
/// <param name="weights">Edge weights</param>
/// <exception cref="ArgumentNullException">Any argument is null</exception>
/// <remarks>This algorithm uses the <seealso cref="BreadthFirstSearchAlgorithm"/>.</remarks>
public BellmanFordShortestPathAlgorithm(
IVertexAndEdgeListGraph <TVertex, TEdge> visitedGraph,
IDictionary <TEdge, double> weights,
IDistanceRelaxer distanceRelaxer
)
: base(visitedGraph, weights, distanceRelaxer)
{
this.predecessors = new Dictionary <TVertex, TVertex>();
}
/// <summary>
/// Initializes a new instance of the <see cref="ShortestPathAlgorithmBase{TVertex,TEdge,TGraph}"/> class.
/// </summary>
/// <param name="host">Host to use if set, otherwise use this reference.</param>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
protected ShortestPathAlgorithmBase(
IAlgorithmComponent host,
TGraph visitedGraph,
Func <TEdge, double> edgeWeights,
IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph)
{
Weights = edgeWeights ?? throw new ArgumentNullException(nameof(edgeWeights));
DistanceRelaxer = distanceRelaxer ?? throw new ArgumentNullException(nameof(distanceRelaxer));
}
/// <summary>
/// Initializes a new instance of the <see cref="UndirectedShortestPathAlgorithmBase{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="host">Host to use if set, otherwise use this reference.</param>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
/// <exception cref="T:System.ArgumentNullException"><paramref name="visitedGraph"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="edgeWeights"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="distanceRelaxer"/> is <see langword="null"/>.</exception>
protected UndirectedShortestPathAlgorithmBase(
[CanBeNull] IAlgorithmComponent host,
[NotNull] IUndirectedGraph <TVertex, TEdge> visitedGraph,
[NotNull] Func <TEdge, double> edgeWeights,
[NotNull] IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph)
{
Weights = edgeWeights ?? throw new ArgumentNullException(nameof(edgeWeights));
DistanceRelaxer = distanceRelaxer ?? throw new ArgumentNullException(nameof(distanceRelaxer));
}
protected RankedShortestPathAlgorithmBase(
IAlgorithmComponent host,
TGraph visitedGraph,
IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph)
{
Contract.Requires(distanceRelaxer != null);
this.distanceRelaxer = distanceRelaxer;
}
/// <summary>
/// Initializes a new instance of the <see cref="BestFirstFrontierSearchAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="host">Host to use if set, otherwise use this reference.</param>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that for a given edge provide its weight.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
public BestFirstFrontierSearchAlgorithm(
[CanBeNull] IAlgorithmComponent host,
[NotNull] IBidirectionalIncidenceGraph <TVertex, TEdge> visitedGraph,
[NotNull] Func <TEdge, double> edgeWeights,
[NotNull] IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph)
{
_edgeWeights = edgeWeights ?? throw new ArgumentNullException(nameof(edgeWeights));
_distanceRelaxer = distanceRelaxer ?? throw new ArgumentNullException(nameof(distanceRelaxer));
}
/// <summary>
/// Initializes a new instance of the <see cref="AStarShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="host">Host to use if set, otherwise use this reference.</param>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="costHeuristic">Function that computes a cost for a given vertex.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
/// <exception cref="T:System.ArgumentNullException"><paramref name="visitedGraph"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="edgeWeights"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="costHeuristic"/> is <see langword="null"/>.</exception>
/// <exception cref="T:System.ArgumentNullException"><paramref name="distanceRelaxer"/> is <see langword="null"/>.</exception>
public AStarShortestPathAlgorithm(
[CanBeNull] IAlgorithmComponent host,
[NotNull] IVertexListGraph <TVertex, TEdge> visitedGraph,
[NotNull] Func <TEdge, double> edgeWeights,
[NotNull] Func <TVertex, double> costHeuristic,
[NotNull] IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph, edgeWeights, distanceRelaxer)
{
CostHeuristic = costHeuristic ?? throw new ArgumentNullException(nameof(costHeuristic));
}
public HoffmanPavleyRankedShortestPathAlgorithm(
IAlgorithmComponent host,
IBidirectionalGraph <TVertex, TEdge> visitedGraph,
Func <TEdge, double> edgeWeights,
IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph, distanceRelaxer)
{
Contract.Requires(edgeWeights != null);
this.edgeWeights = edgeWeights;
}
/// <summary>
/// Initializes a new instance of the <see cref="FloydWarshallAllShortestPathAlgorithm{TVertex,TEdge}"/> class.
/// </summary>
/// <param name="host">Host to use if set, otherwise use this reference.</param>
/// <param name="visitedGraph">Graph to visit.</param>
/// <param name="edgeWeights">Function that computes the weight for a given edge.</param>
/// <param name="distanceRelaxer">Distance relaxer.</param>
public FloydWarshallAllShortestPathAlgorithm(
[CanBeNull] IAlgorithmComponent host,
[NotNull] IVertexAndEdgeListGraph <TVertex, TEdge> visitedGraph,
[NotNull] Func <TEdge, double> edgeWeights,
[NotNull] IDistanceRelaxer distanceRelaxer)
: base(host, visitedGraph)
{
_weights = edgeWeights ?? throw new ArgumentNullException(nameof(edgeWeights));
_distanceRelaxer = distanceRelaxer ?? throw new ArgumentNullException(nameof(distanceRelaxer));
_data = new Dictionary <SEquatableEdge <TVertex>, VertexData>();
}
private void Search(
IVertexListGraph<string, Edge<string>> g,
string root, IDistanceRelaxer relaxer)
{
DagShortestPathAlgorithm<string, Edge<string>> algo =
new DagShortestPathAlgorithm<string, Edge<string>>(
g,
DagShortestPathAlgorithm<string, Edge<string>>.UnaryWeightsFromVertexList(g),
relaxer
);
VertexPredecessorRecorderObserver<string, Edge<string>> predecessors = new VertexPredecessorRecorderObserver<string, Edge<string>>();
predecessors.Attach(algo);
algo.Compute(root);
Verify(algo, predecessors);
}
