/// <summary>
/// Apply random mutation using a mutation factor, default is 0.01
/// </summary>
public Gene Mutate(Gene gene, float mutationFactor = 0.01f)
{
var backup = new Gene(gene);
for (int i = 0; i < gene.Count; i++)
{
var mutate = Utility.CheckProbability(mutationFactor);
if (mutate)
{
var randomType = Utility.GetRandomAction();
Action action = null;
switch (randomType)
{
case ActionType.Move:
action = new MoveAction();
break;
case ActionType.Turn:
action = new TurnAction();
break;
case ActionType.Look:
action = new LookAction(_objectiveAgent, _escapeAgent);
break;
}
gene[i] = action;
}
}
//discard mutation if not valid
return(!gene.IsValid() ? backup : gene);
}
/// <summary>
/// Returns the offspring genes resulting from a single point crossover chosen at random
/// </summary>
public Gene[] SinglePointCrossover(Gene parent1, Gene parent2)
{
var crossoverPosition = UnityEngine.Random.Range(0, _geneSize);
var offspring1 = new List <Action>();
var offspring2 = new List <Action>();
for (int chromosome = 0; chromosome < _geneSize; chromosome++)
{
var p1 = parent1[chromosome];
var p2 = parent2[chromosome];
var swap = crossoverPosition >= chromosome;
if (swap)
{
offspring2.Add(p1);
offspring1.Add(p2);
}
else
{
offspring1.Add(p1);
offspring2.Add(p2);
}
}
var child1 = new Gene(offspring1);
var child2 = new Gene(offspring2);
if (!child1.IsValid() || !child2.IsValid())
{
return(SinglePointCrossover(parent1, parent2));
}
return(new Gene[]
{
child1,
child2
});
}
/// <summary>
/// Returns 2 offsprings using Uniform UniformCrossover, by default using 0.5 ratio
/// </summary>
public Gene[] UniformCrossover(Gene parent1, Gene parent2, float crossoverRatio = 0.5f)
{
var offspring1 = new List <Action>();
var offspring2 = new List <Action>();
for (int chromosome = 0; chromosome < _geneSize; chromosome++)
{
var p1 = parent1[chromosome];
var p2 = parent2[chromosome];
var swap = Utility.CheckProbability(crossoverRatio);
if (swap)
{
offspring2.Add(p1);
offspring1.Add(p2);
}
else
{
offspring1.Add(p1);
offspring2.Add(p2);
}
}
var child1 = new Gene(offspring1);
var child2 = new Gene(offspring2);
if (!child1.IsValid() || !child2.IsValid())
{
return(UniformCrossover(parent1, parent2, crossoverRatio));
}
return(new Gene[]
{
child1,
child2
});
}