public void PageRank()
{
var graph = new BidirectionalGraph <string, Edge <string> >();
graph.AddVerticesAndEdgeRange(new[]
{
new Edge <string>("Amazon", "Twitter"),
new Edge <string>("Amazon", "Microsoft"),
new Edge <string>("Microsoft", "Amazon"),
new Edge <string>("Microsoft", "Facebook"),
new Edge <string>("Microsoft", "Twitter"),
new Edge <string>("Microsoft", "Apple"),
new Edge <string>("Facebook", "Amazon"),
new Edge <string>("Facebook", "Twitter"),
new Edge <string>("Twitter", "Microsoft"),
new Edge <string>("Apple", "Twitter")
});
var algorithm = new PageRankAlgorithm <string, Edge <string> >(graph);
algorithm.Compute();
IEnumerable <string> order = algorithm.Ranks.OrderByDescending(pair => pair.Value).Select(pair => pair.Key);
CollectionAssert.AreEqual(
new[] { "Microsoft", "Twitter", "Amazon", "Facebook", "Apple" },
order);
Assert.Positive(algorithm.GetRanksSum());
double rankSum = algorithm.Ranks.Sum(pair => pair.Value);
Assert.AreEqual(rankSum, algorithm.GetRanksSum());
Assert.Positive(algorithm.GetRanksSum());
Assert.AreEqual(rankSum / graph.VertexCount, algorithm.GetRanksMean());
}
public void Constructor_Throws()
{
var graph = new BidirectionalGraph <int, Edge <int> >();
// ReSharper disable ObjectCreationAsStatement
// ReSharper disable once AssignNullToNotNullAttribute
Assert.Throws <ArgumentNullException>(
() => new PageRankAlgorithm <int, Edge <int> >(null));
var algorithm = new PageRankAlgorithm <int, Edge <int> >(graph);
Assert.Throws <ArgumentOutOfRangeException>(() => algorithm.Damping = -10.0);
Assert.Throws <ArgumentOutOfRangeException>(() => algorithm.Damping = -0.01);
Assert.Throws <ArgumentOutOfRangeException>(() => algorithm.Damping = 1.01);
Assert.Throws <ArgumentOutOfRangeException>(() => algorithm.Damping = 10.0);
Assert.Throws <ArgumentOutOfRangeException>(() => algorithm.Tolerance = -10.0);
Assert.Throws <ArgumentOutOfRangeException>(() => algorithm.Tolerance = -1);
Assert.Throws <ArgumentOutOfRangeException>(() => algorithm.MaxIterations = -10);
Assert.Throws <ArgumentOutOfRangeException>(() => algorithm.MaxIterations = -1);
// ReSharper restore ObjectCreationAsStatement
}
public void Constructor()
{
var graph = new BidirectionalGraph <int, Edge <int> >();
var algorithm = new PageRankAlgorithm <int, Edge <int> >(graph);
AssertAlgorithmProperties(algorithm, graph);
algorithm = new PageRankAlgorithm <int, Edge <int> >(graph)
{
Damping = 0.96
};
AssertAlgorithmProperties(algorithm, graph, 0.96);
algorithm = new PageRankAlgorithm <int, Edge <int> >(graph)
{
Tolerance = double.Epsilon
};
AssertAlgorithmProperties(algorithm, graph, t: double.Epsilon);
algorithm = new PageRankAlgorithm <int, Edge <int> >(graph)
{
MaxIterations = 12
};
AssertAlgorithmProperties(algorithm, graph, iterations: 12);
algorithm = new PageRankAlgorithm <int, Edge <int> >(graph)
{
Damping = 0.91,
Tolerance = 3 * double.Epsilon,
MaxIterations = 50
};
AssertAlgorithmProperties(algorithm, graph, 0.91, 3 * double.Epsilon, 50);
#region Local function
void AssertAlgorithmProperties <TVertex, TEdge>(
PageRankAlgorithm <TVertex, TEdge> algo,
IBidirectionalGraph <TVertex, TEdge> g,
double d = -1,
double t = -1,
int iterations = -1)
where TEdge : IEdge <TVertex>
{
AssertAlgorithmState(algo, g);
CollectionAssert.IsEmpty(algo.Ranks);
if (d >= 0)
{
Assert.AreEqual(d, algo.Damping);
}
else
{
Assert.GreaterOrEqual(algo.Damping, 0);
Assert.LessOrEqual(algo.Damping, 1);
}
if (t >= 0)
{
Assert.AreEqual(t, algo.Tolerance);
}
else
{
Assert.GreaterOrEqual(algo.Tolerance, 0);
}
if (iterations > 0)
{
Assert.AreEqual(iterations, algo.MaxIterations);
}
else
{
Assert.Positive(algo.MaxIterations);
}
}
#endregion
}
