internal static SparseSet CreateNearestNeighourSet(IProblem problem, IList <int> customers, int n)
{
// initialize sparse set.
SparseSet set = new SparseSet();
// loop over all customers and add their n-nearest neigbours.
foreach (int customer in customers)
{
// initialize nearest list.
SortedSet <KeyValuePair <double, int> > nearest_customers = new SortedSet <KeyValuePair <double, int> >(
new SortedSetComparer());
// build nearest list.
double highest_weight = double.MaxValue;
foreach (int neigbour in customers)
{
if (neigbour != customer)
{ // do not
// calculate weight
double weight = problem.Weight(customer, neigbour);
// add to nearest list if needed.
if (weight < highest_weight)
{
nearest_customers.Add(new KeyValuePair <double, int>(weight, neigbour));
// remove highest weight.
if (nearest_customers.Count > n)
{
nearest_customers.Remove(nearest_customers.Max);
}
// set highest weight again.
if (nearest_customers.Count == n)
{
highest_weight = nearest_customers.Max.Key;
}
}
}
}
// add nearest list to sparseset.
foreach (KeyValuePair <double, int> neigbour_pair in nearest_customers)
{
set.Add(new Edge()
{
From = customer,
To = neigbour_pair.Value,
Weight = neigbour_pair.Key
});
}
}
return(set);
}
internal static SparseSet CreateNonSparseSet(IProblem problem, IList <int> customers)
{
// initialize sparse set.
SparseSet set = new SparseSet();
// loop over all customers
foreach (int customer in customers)
{
// loop over all customers again.
foreach (int neighbour in customers)
{
if (neighbour != customer)
{ // do not
set.Add(new Edge()
{
From = customer,
To = neighbour,
Weight = problem.Weight(customer, neighbour)
});
}
}
}
return(set);
}
