private static void CompareAlgorithms <TVertex, TEdge, TGraph>(
[NotNull] AdjacencyGraph <TVertex, TEdge> graph,
[NotNull, InstantHandle] Func <TEdge, double> getDistances,
[NotNull, InstantHandle] Func <AdjacencyGraph <TVertex, TEdge>, Func <TEdge, double>, ShortestPathAlgorithmBase <TVertex, TEdge, TGraph> > shortestPathAlgorithmFactory)
where TEdge : IEdge <TVertex>
where TGraph : IVertexSet <TVertex>
{
// Compute all paths
var algorithm = new FloydWarshallAllShortestPathAlgorithm <TVertex, TEdge>(graph, getDistances);
algorithm.Compute();
TVertex[] vertices = graph.Vertices.ToArray();
foreach (TVertex source in vertices)
{
ShortestPathAlgorithmBase <TVertex, TEdge, TGraph> otherAlgorithm = shortestPathAlgorithmFactory(graph, getDistances);
var predecessors = new VertexPredecessorRecorderObserver <TVertex, TEdge>();
using (predecessors.Attach(otherAlgorithm))
otherAlgorithm.Compute(source);
TryFunc <TVertex, IEnumerable <TEdge> > otherPaths = predecessors.TryGetPath;
foreach (TVertex target in vertices)
{
if (source.Equals(target))
{
continue;
}
bool pathExists = algorithm.TryGetPath(source, target, out IEnumerable <TEdge> floydPath);
Assert.AreEqual(pathExists, otherPaths(target, out IEnumerable <TEdge> otherPath));
if (pathExists)
{
TEdge[] floydEdges = floydPath.ToArray();
CheckPath(source, target, floydEdges);
TEdge[] otherEdges = otherPath.ToArray();
CheckPath(source, target, otherEdges);
// All distances are usually 1 in this test, so it should at least
// be the same number
if (otherEdges.Length != floydEdges.Length)
{
Assert.Fail("Path do not have the same length.");
}
// Check path length are the same
double floydLength = floydEdges.Sum(getDistances);
double otherLength = otherEdges.Sum(getDistances);
if (Math.Abs(floydLength - otherLength) > double.Epsilon)
{
Assert.Fail("Path do not have the same length.");
}
}
}
}
}
protected static void TryGetDistance_Throws_Test <TVertex, TEdge, TGraph>(
[NotNull] ShortestPathAlgorithmBase <TVertex, TEdge, TGraph> algorithm)
where TVertex : class, new()
where TEdge : IEdge <TVertex>
where TGraph : IVertexSet <TVertex>
{
// ReSharper disable once AssignNullToNotNullAttribute
Assert.Throws <ArgumentNullException>(() => algorithm.TryGetDistance(null, out _));
var vertex = new TVertex();
Assert.Throws <InvalidOperationException>(() => algorithm.TryGetDistance(vertex, out _));
}
protected static void TryGetDistance_Test <TEdge, TGraph>(
[NotNull] ShortestPathAlgorithmBase <int, TEdge, TGraph> algorithm)
where TEdge : IEdge <int>
where TGraph : IVertexSet <int>
{
const int vertex1 = 1;
algorithm.Compute(vertex1);
Assert.IsTrue(algorithm.TryGetDistance(vertex1, out double distance));
Assert.AreEqual(algorithm.Distances[vertex1], distance);
const int vertex2 = 2;
Assert.IsFalse(algorithm.TryGetDistance(vertex2, out _));
}
