public void RemoveNeighborBiDirection(Vertex vertex)
{
RemoveNeighbor(vertex);
vertex.RemoveNeighbor(this);
}
public void RemoveNeighbor(Vertex vertex)
{
Neighbors.Remove(vertex);
}
public Vertex(Vertex vertex)
{
Id = vertex.Id;
Name = vertex.Name;
}
public bool AddNeighborBiDirection(Vertex vertex)
{
return(AddNeighbor(vertex) && vertex.AddNeighbor(this));
}
/// <summary>
/// Generate graph by Holme & Kim model
/// </summary>
/// <param name="n">Number of vertices</param>
/// <param name="m0">Number of fundamental nodes</param>
/// <param name="m">Number of edges for new created vertices</param>
/// <para name="p">Probability of making a triad formation</para>
/// <returns></returns>
public Graph GenerateHolmeKimModel(int n, int m0, int m, double p)
{
var vertices = Enumerable.Range(0, m0).Select(id => new Vertex(id)).ToList();
// create base graph (complete graph)
for (int i = 0; i < m0; i++)
{
for (int j = 0; j < m0; j++)
{
if (i == j)
{
continue;
}
vertices[i].AddNeighborBiDirection(vertices[j]);
}
}
var vertexDegreeDistribution = new List <int>();
foreach (var vertex in vertices)
{
for (int i = 0; i < vertex.Degree; i++)
{
vertexDegreeDistribution.Add(vertex.Id);
}
}
// add new nodes
for (int i = m0; i < n; i++)
{
var vertex = new Vertex(m0 + i + 1);
var usedNodeIds = new List <int>();
Vertex newNeighbor = null;
for (int j = 0; j < m; j++)
{
if (j == 0 || p < _random.NextDouble())
{
int randomIndex = _random.Next(vertexDegreeDistribution.Count - 1);
while (usedNodeIds.Contains(vertexDegreeDistribution[randomIndex]))
{
randomIndex = _random.Next(vertexDegreeDistribution.Count - 1);
}
newNeighbor = vertices.Single(e => e.Id == vertexDegreeDistribution[randomIndex]);
bool isAdded = newNeighbor.AddNeighborBiDirection(vertex);
usedNodeIds.Add(vertexDegreeDistribution[randomIndex]);
}
else
{
if (newNeighbor == null)
{
throw new Exception();
}
var possibleNeighborsToAdd = newNeighbor.Neighbors.Except(new[] { vertex }).ToList();
var otherNeighbor = possibleNeighborsToAdd[_random.Next(possibleNeighborsToAdd.Count)];
vertex.AddNeighborBiDirection(otherNeighbor);
}
}
for (int j = 0; j < m; j++)
{
vertexDegreeDistribution.Add(vertex.Id);
vertexDegreeDistribution.Add(vertex.Neighbors[j].Id);
}
vertices.Add(vertex);
}
return(new Graph(vertices));
}
