遗传算法求x^2+y^2的最大值，C++实现

最近和学院的教授开始学习数据挖掘和机器学习的课程，第一步就是学习简单的遗传算法。

在网上找了篇教程，于是将其实现。文章地址文章地址。

内容是求求f(x1,x2)=x1^2+x2^2的最大值 ，x1∈{1,2,3,4,5,6,7} , x2∈{1,2,3,4,5,6,7} 。

选择样本数量为8，经过100代的迭代，效果还不错

代码如下：

/***遗传算法求f(x1,x2)=x1^2+x2^2的最大值 **x1∈{1,2,3,4,5,6,7} , x2∈{1,2,3,4,5,6,7} **@Jet-Muffin*/ #include <iostream>#include <cstdio>#include <cstring>#include <string>#include <algorithm>#include <cmath>#include <vector>#include <map>#include <queue>#include <ctime>using namespace std;#define SAMPLE_NUM 8     //样本数量 #define EVOLVE_NUM 300   //进化代数 #define random(x) (rand()%x)   //随机函数 #define VARIATE_RATE 10  //变异率 void init();void output();void cross();void cross_change(int a,int b);//样本node struct node{int bin[6];int x1,x2;int f;double pct;}group[SAMPLE_NUM];//样本集合group node temp[SAMPLE_NUM];    //操作中间变量数组 int choosen[SAMPLE_NUM];  //概率分布区域数组 //初始化，随机生成样本 void init(){for(int i = 0; i < SAMPLE_NUM; i++){//随机生成bin数组 for(int j = 0; j < 6; j++){int pct = random(100);  if(pct >= 50) group[i].bin[j] = 1;elsegroup[i].bin[j] = 0; }}}//计算相应数值 void calcu(){for(int i = 0; i < SAMPLE_NUM; i++){//生成相应x1、x2int base = 1;group[i].x1 = group[i].x2 = 0;for(int j = 6 / 2 - 1; j >= 0; j--){group[i].x1 += base * group[i].bin[j];base *= 2;} base = 1;for(int j = 6 - 1; j >= 6 / 2; j--){group[i].x2 += base * group[i].bin[j];base *= 2;} //计算相应适值group[i].f = group[i].x1 * group[i].x1 + group[i].x2 * group[i].x2;//计算占总数百分比 int totf = 0;for(int i = 0; i < SAMPLE_NUM; i++)totf += group[i].f;for(int i = 0; i < SAMPLE_NUM; i++)group[i].pct = group[i].f / (double)totf; }}//选择过程 void choose(){cout<<endl;cout<<"Choosen:......."<<endl;memset(choosen,0,sizeof(choosen));//计算概率区域 choosen[0] = floor(group[0].pct * 100 + 0.5);for(int i = 1; i < SAMPLE_NUM - 1; i++){choosen[i] = choosen[i-1] + floor(group[i].pct * 100 + 0.5);}choosen[SAMPLE_NUM - 1] = 100;cout<<"Posibility Area: ";for(int i = 0; i < SAMPLE_NUM; i++)cout<<choosen[i]<<" ";cout<<endl;//生成随机数以模拟选择 for(int i = 0; i < SAMPLE_NUM; i++){int pct = random(100);int choosen_node;for(int j = 1; j < SAMPLE_NUM; j++) if(pct < choosen[j]) {choosen_node = j;break;}cout<<"seed:"<<pct<<", ";cout<<"node "<<choosen_node + 1<<" was choosen"<<endl;temp[i] = group[choosen_node];}//输出选择结果 cout<<"choosen result:"<<endl;for(int i = 0; i < SAMPLE_NUM; i++){cout<<"temp["<<i + 1<<"]: ";for(int j = 0; j < 6; j++)cout<<temp[i].bin[j]<<" ";cout<<endl; }}//交叉运算 void cross(){cout<<endl;cout<<"Crossing:...."<<endl;cout<<"Matching:..."<<endl;//用vector的random_shuffle实现随机乱序配对，从vector中取两个node就进行运算，实现随机交叉 vector<int> seeds;for (int i = 0; i < SAMPLE_NUM; i++)          seeds.push_back(i + 1);      random_shuffle(seeds.begin(), seeds.end());      int cnt = 0;    int pair_fst,pair_sec;    for(vector<int>::iterator it = seeds.begin(); it != seeds.end(); it++)    {    cnt++;    if(cnt&1)pair_fst = *it;elsepair_sec = *it;if(cnt == 2){cout<<"Matching result: "<<pair_fst<<"-"<<pair_sec<<endl;cnt = 0;cross_change(pair_fst - 1,pair_sec - 1);}    }    //输出交换结果 cout<<"cross result:"<<endl;for(int i = 0; i < SAMPLE_NUM; i++){cout<<"temp["<<i + 1<<"]: ";for(int j = 0; j < 6; j++)cout<<temp[i].bin[j]<<" ";cout<<endl; }    cout<<endl;}//交叉运算过程 void cross_change(int a,int b){//生成交叉点 int cross_seed = random(4) + 1;cout<<"cross position:"<<cross_seed<<endl; //输出交换前串信息 cout<<"temp["<<a + 1<<"]: ";for(int i = 0; i < 6; i++){if(i == cross_seed) cout<<"| ";cout<<temp[a].bin[i]<<" ";}cout<<endl;cout<<"temp["<<b + 1<<"]: ";for(int i = 0; i < 6; i++){if(i == cross_seed) cout<<"| ";cout<<temp[b].bin[i]<<" ";}cout<<endl;//进行交换 for(int i = cross_seed; i < 6; i++){int tmp;tmp = temp[a].bin[i];temp[a].bin[i] = temp[b].bin[i];temp[b].bin[i] = tmp; }} //变异运算 void variation(){cout<<"Variation:"<<endl;for(int i = 0; i < SAMPLE_NUM; i++){cout<<"temp["<<i<<"]:";int position_seed = random(5);cout<<"variate pos: "<<position_seed<<",";int var_seed = random(100);if(var_seed < VARIATE_RATE){cout<<" success";if(temp[i].bin[position_seed]) temp[i].bin[position_seed] = 0;elsetemp[i].bin[position_seed] = 1;}cout<<endl;}    //输出变异结果 cout<<"variate result:"<<endl;for(int i = 0; i < SAMPLE_NUM; i++){cout<<"temp["<<i + 1<<"]: ";for(int j = 0; j < 6; j++)cout<<temp[i].bin[j]<<" ";cout<<endl; }cout<<endl;}//将运算的temp数组赋值给group数组以方便下一次迭代运算 void trans(){for(int i = 0; i < SAMPLE_NUM; i++)group[i] = temp[i];}//输出信息 void output(){for(int i = 0; i < SAMPLE_NUM; i++){cout<<"node["<<i + 1<<"]: ";for(int j = 0; j < 6; j++)cout<<group[i].bin[j]<<" ";cout<<" x1: "<<group[i].x1;cout<<" x2: "<<group[i].x2;cout<<" f: "<<group[i].f;cout<<" percent:"<<group[i].pct<<endl;}cout<<endl;} //总函数接口 void evolution(){init();calcu(); output();for(int i = 0; i < EVOLVE_NUM; i++){choose();cross(); variation();trans();calcu(); output();}}int main(){srand((int)time(0));evolution();}

结果：

该函数最大值为98，有7个样本进化到了该数值，还有1个样本为次大值，效果不错。