// 选择用于交叉的个体，确保最差的个体不会进来
private static GiftTicketIndividual TournamentSelection(GiftTicketPopulation pop)
{
GiftTicketPopulation tournament = new GiftTicketPopulation(tournamentSize, false);
for (int i = 0; i < tournamentSize; i++)
{
int randomId = (int)(new Random().NextDouble() * pop.Size());
tournament.SaveIndividual(i, pop.GetIndividual(randomId));
}
GiftTicketIndividual fittest = tournament.GetFittest();
return(fittest);
}
// 进化一个种群
public static GiftTicketPopulation EvolvePopulation(GiftTicketPopulation pop)
{
GiftTicketPopulation newPopulation = new GiftTicketPopulation(pop.Size(), false);
// 保留最优秀的个体
if (elitism)
{
newPopulation.SaveIndividual(0, pop.GetFittest());
}
// 交叉种群
int elitismOffset;
if (elitism)
{
elitismOffset = 1;
}
else
{
elitismOffset = 0;
}
// 交叉产生新的个体
for (int i = elitismOffset; i < pop.Size(); i++)
{
// Console.WriteLine("交叉产生新个体");
//确保不要把最差的个体选进来
GiftTicketIndividual indiv1 = TournamentSelection(pop);
GiftTicketIndividual indiv2 = TournamentSelection(pop);
GiftTicketIndividual newIndiv = Crossover(indiv1, indiv2);
newPopulation.SaveIndividual(i, newIndiv);
}
// 变异
for (int i = elitismOffset; i < newPopulation.Size(); i++)
{
Mutate(newPopulation.GetIndividual(i));
}
return(newPopulation);
}