//遗传算法，选择--从染色体池中选择一个染色体--（天择）
//找出适应度低于随机数的个体出来----轮盘赌算法
private Chomosone SelectFrom(List <Chomosone> pool)
{
Chomosone individual = null;
//Calc the total fitness
float total = 0f;
for (int i = pool.Count - 1; i >= 0; i--)
{
total += 1.0f / pool[i].fitness; //此处求1除以每个适应因子，再求和
}
float slice = (float)(total * rand.NextDouble());
//Loop to find the individual
float next = 0f;
for (int i = pool.Count - 1; i >= 0; i--)
{
next += 1.0f / pool[i].fitness;
if (next >= slice)
{
individual = pool[i];
break;
}
}
if (individual == null)
{
individual = pool[pool.Count - 1];
}
pool.Remove(individual);
return(individual);
}
//防止进化过程中产生的最优解被交叉和变异所破坏，可以将每一代中的最优解原封不动的复制到下一代中
public object Clone()
{
var genesClone = (List <DNA>)genes.Clone <DNA>();
Chomosone clone = new Chomosone(genesClone);
clone.fitness = this.fitness;
clone.Bounds = this.Bounds;
return(clone);
}
//遗传算子，模拟生物进化
public Chomosone OnProcess(List <int> rawIds)
{
List <Chomosone> pool = new List <Chomosone>(); //原始库挑选
List <Chomosone> remain = new List <Chomosone>(); //进化后剩下来的
for (int i = 0; i < poolSize; i++)
{
pool.Add(new Chomosone(rawIds));
}
float minFitness = float.MaxValue;
int count = 0;
Chomosone chomosone = null;
while (count < 1)
{
remain.Clear();
for (int x = pool.Count - 1; x >= 0; x -= 2)
{
Chomosone c0 = SelectFrom(pool);
Chomosone c1 = SelectFrom(pool);
c0.CrossOver(c1);
c0.Mutate();
c1.Mutate();
c0.Place();
c1.Place();
remain.Add(c0);
remain.Add(c1);
}
pool.AddRange(remain);
count++;
//按照适应度大小从小到大排序，从剩余中找出适应度最小的个体
var best = pool.OrderBy(cho => cho.fitness).First();
if (best.fitness != 1 && best.fitness < minFitness)
{
minFitness = best.fitness;
chomosone = (Chomosone)best.Clone();//每次循环找出最优个体
}
}
Debug.Log("Min fitness : " + minFitness);
Debug.Log("Chom fitness : " + chomosone.fitness);
//---返回适应度最小的个体
return(chomosone);
}
//遗传算法交叉操作--交换随机数和基因长度之间的基因
//genes是一个List<DNA>集合，交换集合中DNA的顺序
public void CrossOver(Chomosone other)
{
//产生一个随机数，根据随机数大小和突变概率比较，大则发生交叉事件
if (rand.NextDouble() > crossRate)
{
return;
}
var chomLength = genes.Count;
int pos = rand.Next(chomLength);
for (int x = pos; x < chomLength; x++)
{
var tmpDNA = genes[x];
genes[x] = other.genes[x];
other.genes[x] = tmpDNA;
}
}
