// 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);
}
public GiftTicketIndividual GetFittest()
{
GiftTicketIndividual fittest = individuals[0];
// 取得适应度最高的个体作为种群的适应度
for (int i = 0; i < Size(); i++)
{
if (fittest.GetFitness() <= GetIndividual(i).GetFitness())
{
fittest = GetIndividual(i);
}
}
return(fittest);
}
// 建立一个总群
public GiftTicketPopulation(int populationSize, bool initialise)
{
individuals = new GiftTicketIndividual[populationSize];
// 初始化种群
if (initialise)
{
// 建立每一个个体
for (int i = 0; i < Size(); i++)
{
GiftTicketIndividual newIndividual = new GiftTicketIndividual();
newIndividual.GenerateIndividual(GiftTicketAlgorithm.RetailDetails, GiftTicketAlgorithm.Tickets);
SaveIndividual(i, newIndividual);
}
}
}
// 计算某一个个体的适应度,最重要的地方
public static int GetFitness(GiftTicketIndividual individual)
{
int fitness = 0;
// 个体和候选解比较，约接近候选集，适应度越高
for (int i = 0; i < individual.Size(); i++)
{//所有优惠总和
fitness += individual.GetGene(i).DiscountMoney();
//截止日期越前越优先使用
if (individual.GetGene(i).Ticket != null)
{
TimeSpan ts = individual.GetGene(i).Ticket.ExpiredDate - DateTime.Now;
//这个影响比较大，暂时不计算过期时间
// fitness -= ts.Days;
}
}
return(fitness);
}
// 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);
}
// 变异
private static void Mutate(GiftTicketIndividual indiv)
{
// Console.WriteLine("变异");
// Loop through genes
for (int i = 0; i < indiv.Size(); i++)
{
if (new Random().NextDouble() <= mutationRate)
{
//从剩余的优惠券中，随机一个优惠券
GiftTicketMatch gene = indiv.GetGene(i);
GiftTicket ticket = null;
if (indiv.tickets.Count > 0)
{
Random random = new Random(GetRandomSeed());
int pickTicket = random.Next(0, indiv.tickets.Count);
// int pickTicket = (int)(new Random().NextDouble() * indiv.tickets.Count);
ticket = indiv.tickets[pickTicket];
indiv.SetMatch(i, gene, ticket);
}
}
}
}
// 交叉
private static GiftTicketIndividual Crossover(GiftTicketIndividual indiv1, GiftTicketIndividual indiv2)
{
// Console.WriteLine("交叉");
GiftTicketIndividual newSol = new GiftTicketIndividual();
newSol.RetailsOrg = GiftTicketAlgorithm.RetailDetails;
newSol.TicketsOrg = GiftTicketAlgorithm.Tickets;
// Loop through genes
for (int i = 0; i < indiv1.Size(); i++)
{
// 以一定概率交叉,如果优惠券被占用了？？？那么交叉完了之后这个优惠券就变成空？
if (new Random().NextDouble() <= uniformRate)
{
//检查优惠券是否被占用？如果被占用是否还有可以替换的优惠券使用？有就替换掉？
newSol.SetGene(i, indiv1.GetGene(i));
}
else
{
newSol.SetGene(i, indiv2.GetGene(i));
}
}
return(newSol);
}
// Save individual
public void SaveIndividual(int index, GiftTicketIndividual indiv)
{
individuals[index] = indiv;
}