我在实现 GA 框架时采用的方法如下: 创建以下类: Generation GeneticAlgorithm GeneticAlgorithmAdapter GeneticAlgorithmParameters Population Individual
虽然我没有为各种操作实现策略模式,但我相信在 GeneticAlgorithm 实例上创建各种 GA 操作实现作为参数将是微不足道的。
GeneticAlgorithm 类捕获基本算法。它实际上只是定义了各个步骤(种群创建、个体随机化、选择、交叉、突变等),并在算法运行时管理个体种群。我想如果你愿意的话,你可以在这里插入不同的操作。
真正的魔力在于适配器。这就是使问题域(个人的特定子类,及其所有相关数据)适应遗传算法的原因。我在这里大量使用泛型,以便将人口、参数和个体的特定类型传递到实现中。这给了我对适配器实现的智能感知和强类型检查。适配器基本上需要定义如何为给定的个体(及其基因组)执行特定的操作。例如,这是适配器的接口:
/// <summary>
/// The interface for an adapter that adapts a domain problem so that it can be optimised with a genetic algorithm.
/// It is a strongly typed version of the adapter.
/// </summary>
/// <typeparam name="TGA"></typeparam>
/// <typeparam name="TIndividual"></typeparam>
/// <typeparam name="TPopulation"></typeparam>
public interface IGeneticAlgorithmAdapter<TGA, TIndividual, TGeneration, TPopulation> : IGeneticAlgorithmAdapter
where TGA : IGeneticAlgorithm
where TIndividual : class, IIndividual, new()
where TGeneration : class, IGeneration<TIndividual>, new()
where TPopulation : class, IPopulation<TIndividual, TGeneration>, new()
{
/// <summary>
/// This gets called before the adapter is used for an optimisation.
/// </summary>
/// <param name="pso"></param>
void InitialiseAdapter(TGA ga);
/// <summary>
/// This initialises the individual so that it is ready to be used for the genetic algorithm.
/// It gets randomised in the RandomiseIndividual method.
/// </summary>
/// <param name="ga">The genetic algorithm that is running.</param>
/// <param name="individual">The individual to initialise.</param>
void InitialiseIndividual(TGA ga, TIndividual individual);
/// <summary>
/// This initialises the generation so that it is ready to be used for the genetic algorithm.
/// </summary>
/// <param name="ga">The genetic algorithm that is running.</param>
/// <param name="generation">The generation to initialise.</param>
void InitialiseGeneration(TGA ga, TGeneration generation);
/// <summary>
/// This initialises the population so that it is ready to be used for the genetic algorithm.
/// </summary>
/// <param name="ga">The genetic algorithm that is running.</param>
/// <param name="population">The population to initialise.</param>
void InitialisePopulation(TGA ga, TPopulation population);
void RandomiseIndividual(TGA ga, TIndividual individual);
void BeforeIndividualUpdated(TGA ga, TIndividual individual);
void AfterIndividualUpdated(TGA ga, TIndividual individual);
void BeforeGenerationUpdated(TGA ga, TGeneration generation);
void AfterGenerationUpdated(TGA ga, TGeneration generation);
void BeforePopulationUpdated(TGA ga, TPopulation population);
void AfterPopulationUpdated(TGA ga, TPopulation population);
double CalculateFitness(TGA ga, TIndividual individual);
void CloneIndividualValues(TIndividual from, TIndividual to);
/// <summary>
/// This selects an individual from the population for the given generation.
/// </summary>
/// <param name="ga">The genetic algorithm that is running.</param>
/// <param name="generation">The generation to select the individual from.</param>
/// <returns>The selected individual.</returns>
TIndividual SelectIndividual(TGA ga, TGeneration generation);
/// <summary>
/// This crosses over two parents to create two children.
/// </summary>
/// <param name="ga">The genetic algorithm that is running.</param>
/// <param name="parentsGeneration">The generation that the parent individuals belong to.</param>
/// <param name="childsGeneration">The generation that the child individuals belong to.</param>
/// <param name="parent1">The first parent to cross over.</param>
/// <param name="parent2">The second parent to cross over.</param>
/// <param name="child">The child that must be updated.</param>
void CrossOver(TGA ga, TGeneration parentsGeneration, TIndividual parent1, TIndividual parent2, TGeneration childsGeneration, TIndividual child);
/// <summary>
/// This mutates the given individual.
/// </summary>
/// <param name="ga">The genetic algorithm that is running.</param>
/// <param name="generation">The individuals generation.</param>
/// <param name="individual">The individual to mutate.</param>
void Mutate(TGA ga, TGeneration generation, TIndividual individual);
/// <summary>
/// This gets the size of the next generation to create.
/// Typically, this is the same size as the current generation.
/// </summary>
/// <param name="ga">The genetic algorithm that is running.</param>
/// <param name="currentGeneration">The current generation.</param>
/// <returns>The size of the next generation to create.</returns>
int GetNextGenerationSize(TGA ga, TGeneration currentGeneration);
/// <summary>
/// This gets whether a cross over should be performed when creating a child from this individual.
/// </summary>
/// <param name="ga">The genetic algorithm that is running.</param>
/// <param name="currentGeneration">The current generation.</param>
/// <param name="individual">The individual to determine whether it needs a cross over.</param>
/// <returns>True to perform a cross over. False to allow the individual through to the next generation un-altered.</returns>
bool ShouldPerformCrossOver(TGA ga, TGeneration generation, TIndividual individual);
/// <summary>
/// This gets whether a mutation should be performed when creating a child from this individual.
/// </summary>
/// <param name="ga">The genetic algorithm that is running.</param>
/// <param name="currentGeneration">The current generation.</param>
/// <param name="individual">The individual to determine whether it needs a mutation.</param>
/// <returns>True to perform a mutation. False to allow the individual through to the next generation un-altered.</returns>
bool ShouldPerformMutation(TGA ga, TGeneration generation, TIndividual individual);
}
我发现这种方法对我很有效,因为我可以轻松地为不同的问题域重用 GA 实现,只需编写适当的适配器。对于不同的选择、交叉或变异的实现,适配器可以调用它感兴趣的实现。我通常做的是在研究合适的策略时注释掉适配器中的不同想法。
希望这可以帮助。我可以在必要时提供更多指导。很难做到这样的设计正义。