ga_simple.cpp

该代码是用C++编写的遗传算法,可在C++或 matlab环境下都可运行.

#include <iostream>
#include <cstdlib>
#include <cmath>

using std::cout;
using std::endl;

const int maxruns=150;
const int popsize=50;
const int lchrom=2;
unsigned oldpop[popsize][lchrom];
unsigned newpop[popsize][lchrom];
double fitarray[popsize];
double sumfit;
unsigned mate1[lchrom];
unsigned mate2[lchrom];
unsigned child1[lchrom];
unsigned child2[lchrom];
double best=0.0;

void initialize()
{
	unsigned mask=1;
	for(int j=0;j<popsize;++j)
		for (int k=0;k<lchrom;++k)
		{
			oldpop[j][k]=0;
			for (int s=0;s<(8*sizeof(unsigned));++s)
			{
				int a=rand();
	            double sj=static_cast<double>(a)/RAND_MAX;
				if (sj<=0.5)
				{
					oldpop[j][k]=oldpop[j][k]|(mask<<s);
				}
			}
		}
    ////////////////
	cout<<"initialization"<<endl;
	for(int k=0;k<popsize;++k)
	{
		for (int j=0;j<lchrom;++j)
		{
			cout<<oldpop[k][j]<<"    ";
			if (j==lchrom-1)
				cout<<endl;
		}
	}
	///////////
}



double objfun(int p)
{
	unsigned mask=1;
	int bitpos;
	unsigned tp;
	double sum=0;
	double v;
	double dvalue;
	double fitness;



	for(int k=0;k<lchrom;++k)
	{
		tp=oldpop[p][k];
		for(int j=1;j<=8*sizeof(unsigned);++j)
		{
			bitpos=8*sizeof(unsigned)*k+j;
			if ((tp&mask)==1)
			{
				v=pow(2,(bitpos-1));
				sum=sum+v;
			}
			tp=tp>>1;
		}
	}

	dvalue=-1+3*sum/(pow(2.0,lchrom*8*sizeof(unsigned))-1);
	fitness=dvalue*sin(40*atan(1)*dvalue)+2.0;

	return fitness;

}


void preselect()
{
	
	sumfit=0;
	for(int i=0;i<popsize;++i)
	{
		fitarray[i]=objfun(i);
		sumfit+=fitarray[i];
		if(best<fitarray[i])  best=fitarray[i];
		
	}
	
}


int select()
{
	
	int f;
	int a=rand();
	double sj=static_cast<double>(a)/RAND_MAX;
	double sjfit=sj*sumfit;
    double sum=fitarray[0];
	for(int i=0;i<popsize;++i)
	{
		if (sjfit<=sum)
		{
			f=i;
			break;
		}
		else
		{
			sum+=fitarray[i+1];
		}
	}
	
	
	return f;
}


void crossover()
{
	
	unsigned mask;
	unsigned temp=1;
	int a=rand();
    double pc=static_cast<double>(a)/RAND_MAX;
	
	if (pc<=0.25)
	{
		int crosspos=1+rand()%(8*lchrom*sizeof(unsigned)-1);
        
		for(int k=1;k<=lchrom;++k)
		{
			if (crosspos>=(k*8*sizeof(unsigned)))
			{
				child1[k-1]=mate1[k-1];
				child2[k-2]=mate2[k-1];
			}
			else if ((crosspos<(k*8*sizeof(unsigned)))&&(crosspos>((k-1)*8*sizeof(unsigned))))
			{
				mask=0;
				for (int j=1;j<=(crosspos-((k-1)*8*sizeof(unsigned)));++j)
				{
					mask=mask<<1;
					mask=mask|temp;
				}
				child1[k-1]=((mate1[k-1]&mask)|(mate2[k-1]&(~mask)));
				child2[k-1]=((mate1[k-1]&(~mask))|(mate2[k-1]&mask));
			}
			else
			{
				child1[k-1]=mate2[k-1];
				child2[k-1]=mate1[k-1];
			}
		}
		
	}
	else
	{
		for (int k=0;k<lchrom;++k)
		{
			child1[k]=mate1[k];
			child2[k]=mate2[k];
		}
	}
	
}


void mutation()
{
	
	int a;
	double pm;
	unsigned mask;
	unsigned temp=1;
	
	
	for (int k=0;k<lchrom;++k)
	{
		for (int j=0;j<8*sizeof(unsigned);++j)
		{
			a=rand();
            pm=static_cast<double>(a)/RAND_MAX;
			if (pm<=0.01)
			{
				mask=(temp<<j);
				child1[k]=child1[k]^mask;
			}
		}
	}

	for (int n=0;n<lchrom;++n)
	{
		for (int j=0;j<8*sizeof(unsigned);++j)
		{
			a=rand();
            pm=static_cast<double>(a)/RAND_MAX;
			if (pm<=0.01)
			{
				mask=(temp<<j);
				child2[n]=child2[n]^mask;
			}
		}
	}
}




int main()
{
	initialize();
	
    for(int d=0;d<maxruns;++d)
	{
		preselect();
		int par;
		
		for(int b=0;b<popsize;b+=2)
		{		    
			par=select();
		    for (int v=0;v<lchrom;++v)
				mate1[v]=oldpop[par][v];
			
		    par=select();
		    for (int u=0;u<lchrom;++u)
				mate2[u]=oldpop[par][u];
		    crossover();
			mutation();
		    
			for (int l=0;l<lchrom;++l)
			{
				newpop[b][l]=child1[l];
				newpop[b+1][l]=child2[l];
			}
		
		}
        
		for(int h=0;h<popsize;++h)
			for(int j=0;j<lchrom;++j)
				oldpop[h][j]=newpop[h][j];
        
		for (int g=0;g<popsize;++g)
			cout<<fitarray[g]<<" ";
		cout<<endl;
	}

		
		cout<<endl<<endl;
		cout<<best;
		return 0;
}