public double GraphAssortativity2()
{
cacheIsEmpty = false;
if (!Double.IsNegativeInfinity(_graphAssortativity2))
{
return(_graphAssortativity2);
}
if (ExcessDegreeVariance == 0) // All vertices are the same degree, automatically perfect assortativity
{
return(_graphAssortativity2 = 1.0);
}
double M = Edges.Count();
double numerator = ((1 / M) * (EdgesAsNodes.Sum(e => e.Item1.Degree * e.Item2.Degree)) -
Math.Pow((1 / M) * 0.5 * EdgesAsNodes.Sum(e => e.Item1.Degree + e.Item2.Degree), 2.0));
double denominator = ((1 / M) * 0.5 *
EdgesAsNodes.Sum(e => Math.Pow(e.Item1.Degree, 2) + Math.Pow(e.Item2.Degree, 2)) -
Math.Pow((1 / M) * 0.5 * EdgesAsNodes.Sum(e => e.Item1.Degree + e.Item2.Degree), 2.0));
return(_graphAssortativity2 = numerator / denominator);
}
