/// <summary>
/// Main process loop for performing a crossover on a population.
/// </summary>
protected void Process()
{
int maxLoop = 100;
int eliteCount = 0;
//reset the number of evaluations
_evaluations = 0;
//now that we know how many children we are to be creating, in the case of 'Delete Last'
//we copy the current generation across and add new children where they are greater than
//the worst solution.
if (_replacementMethodS == ReplacementMethod.DeleteLast)
{
//copy everything accross including the elites
NewPopulation.Solutions.Clear();
NewPopulation.Solutions.AddRange(CurrentPopulation.Solutions);
}
else
{
//just copy the elites, this will take all elites
//TODO: Sort out what we do if we overfill the population with elites
var elites = CurrentPopulation.GetElites();
eliteCount = elites.Count();
if (elites != null && eliteCount > 0)
{
NewPopulation.Solutions.AddRange(elites);
}
}
_currentPopulationSize = CurrentPopulation.Solutions.Count;
_numberOfChildrenToGenerate =
_currentPopulationSize - eliteCount;
while (_numberOfChildrenToGenerate > 0)
{
//emergency exit
if (maxLoop <= 0)
{
throw new ChromosomeException("Unable to create a suitable child. If duplicates have been disallowed then consider increasing the chromosome length or increasing the number of elites.");
}
//these will hold the children
Chromosome c1 = null;
Chromosome c2 = null;
//select some parents
var parents = CurrentPopulation.SelectParents();
var p1 = parents[0];
var p2 = parents[1];
//crossover
PerformCrossover(p1, p2, CrossoverProbability, out c1, out c2);
if (AddChild(c1))
{
_numberOfChildrenToGenerate--;
}
else
{
//unable to create child
maxLoop--;
}
//see if we can add the secomd
if (_numberOfChildrenToGenerate > 0)
{
if (AddChild(c2))
{
_numberOfChildrenToGenerate--;
}
else
{
//unable to create child
maxLoop--;
}
}
}
}