C#实现遗传算法模拟花朵的进化

来源：pcdog 作者：佚名出处：巧巧读书 2008-01-11 进入讨论组

关键词：

以下代码实现了一个简单的花朵进化的模拟过程。
花朵的种群数量是10，共进化了50代。

通过运行程序，你会发现通过不断的进化，种群的总的适应环境的能力在逐步提高（fitness的值下降）。

实现代码：

using System;
using System.Collections.Generic;
using System.Text;

namespace GA
{
   class Program
   {
   static void Main(string[] args)
   {
   World world = new World();

world.Init();

   for (int i = 0; i < 50; i++)
   {
   world.Evolve();

   Console.WriteLine(i);
   world.Show();
   }
   }
   }

   class World
   {
   int kMaxFlowers = 11;

Random Rnd = new Random();

public int[] temperature;

public int[] water;

public int[] sunlight;

public int[] nutrient;

public int[] beneficialInsect;

public int[] harmfulInsect;

public int currentTemperature;

public int currentWater;

public int currentSunlight;

public int currentNutrient;

public int currentBeneficialInsect;

public int currentHarmfulInsect;

   public World()
   {
   temperature = new int[kMaxFlowers];
   water = new int[kMaxFlowers];
   sunlight = new int[kMaxFlowers];
   nutrient = new int[kMaxFlowers];
   beneficialInsect = new int[kMaxFlowers];
   harmfulInsect = new int[kMaxFlowers];
   }

   /**//// <summary>
   /// 初始化第一代花朵的基因结构
   /// </summary>
   public void Init()
   {

   for (int i = 1; i < kMaxFlowers; i++)
   {
   temperature[i] = Rnd.Next(1, 75);

water[i] = Rnd.Next(1, 75);

sunlight[i] = Rnd.Next(1, 75);

nutrient[i] = Rnd.Next(1, 75);

beneficialInsect[i] = Rnd.Next(1, 75);

harmfulInsect[i] = Rnd.Next(1, 75);
}

currentTemperature = Rnd.Next(1, 75);

currentWater = Rnd.Next(1, 75);

currentSunlight = Rnd.Next(1, 75);

currentNutrient = Rnd.Next(1, 75);

currentBeneficialInsect = Rnd.Next(1, 75);

currentHarmfulInsect = Rnd.Next(1, 75);

}

   /**//// <summary>
   /// 越大说明花朵的适应环境的能力差，小说明适应环境的能力强
   /// </summary>
   /// <param name="flower"></param>
   /// <returns></returns>
   private int Fitness(int flower)
   {
   int theFitness = 0;

theFitness = Math.Abs(temperature[flower] - currentTemperature);

theFitness = theFitness + Math.Abs(water[flower] - currentWater);

theFitness = theFitness + Math.Abs(sunlight[flower] -

currentSunlight);

theFitness = theFitness + Math.Abs(nutrient[flower] -

currentNutrient);

theFitness = theFitness + Math.Abs(beneficialInsect[flower] -

currentBeneficialInsect);

theFitness = theFitness + Math.Abs(harmfulInsect[flower] -

currentHarmfulInsect);

return (theFitness);
}

   /**//// <summary>
   /// 排除适应能力差的花朵，让适应能力强的花朵杂交繁殖，产生下一代。同时有一定的概率变异。
   /// </summary>
   public void Evolve()
   {
   int[] fitTemperature = new int[kMaxFlowers];

int[] fitWater = new int[kMaxFlowers];

int[] fitSunlight = new int[kMaxFlowers];

int[] fitNutrient = new int[kMaxFlowers];

int[] fitBeneficialInsect = new int[kMaxFlowers];

int[] fitHarmfulInsect = new int[kMaxFlowers];

int[] fitness = new int[kMaxFlowers];

int i;

int leastFit = 0;

int leastFitIndex = 1;

for (i = 1; i < kMaxFlowers; i++)

if (Fitness(i) > leastFit)
{

leastFit = Fitness(i);

leastFitIndex = i;

}

temperature[leastFitIndex] = temperature[Rnd.Next(1, 10)];

water[leastFitIndex] = water[Rnd.Next(1, 10)];

sunlight[leastFitIndex] = sunlight[Rnd.Next(1, 10)];

nutrient[leastFitIndex] = nutrient[Rnd.Next(1, 10)];

beneficialInsect[leastFitIndex] = beneficialInsect[Rnd.Next(1, 10)];

harmfulInsect[leastFitIndex] = harmfulInsect[Rnd.Next(1, 10)];

for (i = 1; i < kMaxFlowers; i++)
{

fitTemperature[i] = temperature[Rnd.Next(1, 10)];

fitWater[i] = water[Rnd.Next(1, 10)];

fitSunlight[i] = sunlight[Rnd.Next(1, 10)];

fitNutrient[i] = nutrient[Rnd.Next(1, 10)];

fitBeneficialInsect[i] = beneficialInsect[Rnd.Next(1, 10)];

fitHarmfulInsect[i] = harmfulInsect[Rnd.Next(1, 10)];

}

for (i = 1; i < kMaxFlowers; i++)
{

temperature[i] = fitTemperature[i];

water[i] = fitWater[i];

sunlight[i] = fitSunlight[i];

nutrient[i] = fitNutrient[i];

beneficialInsect[i] = fitBeneficialInsect[i];

harmfulInsect[i] = fitHarmfulInsect[i];

}

for (i = 1; i < kMaxFlowers; i++)
{

if (Rnd.Next(1, 100) == 1)

temperature[i] = Rnd.Next(1, 75);

if (Rnd.Next(1, 100) == 1)

water[i] = Rnd.Next(1, 75);

if (Rnd.Next(1, 100) == 1)

sunlight[i] = Rnd.Next(1, 75);

if (Rnd.Next(1, 100) == 1)

nutrient[i] = Rnd.Next(1, 75);

if (Rnd.Next(1, 100) == 1)

beneficialInsect[i] = Rnd.Next(1, 75);

if (Rnd.Next(1, 100) == 1)

harmfulInsect[i] = Rnd.Next(1, 75);

}

   /**//// <summary>
   /// 显示种群中个体对环境的适应能力，还有所有个体对环境的适应能力之和。
   /// </summary>
   public void Show()
   {
   int sum = 0;
   for (int i = 1; i < kMaxFlowers; i++)
   {
   int fitness = Fitness(i);
   sum += fitness;
   Console.WriteLine("No." + i + "'s fitness is " + fitness);
   }

   Console.WriteLine("fitness sum is " + sum);
   }
   }
}

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