public class GA {
final static int N=3; // number of variables
final static int M=1; // number of objectives
final static int TYPE=1; // 1=max;-1=min
final static int GEN=400; // maximum generation number
final static int POP_SIZE=30;
final static double P_MUTATION=0.15 ; //变异概率
final static double P_CROSSOVER=0.7; //交配概率，当随机数小于该值时，该染色体被选中
static double [][] CHROMOSOME=new double [POP_SIZE+1][N+1];
static double [][]OBJECTIVE=new double [POP_SIZE+1][M+1];
static double []q=new double[POP_SIZE+1];
final static long RAND_MAX=1000000;
/////////////////////////////////////
public static double myu(double a, double b) // Uniform Distribution
{
double y;
if(a>b) {
System.out.print("\nThe first parameter should be less than the second!");
//exit(1);
}
y = Math.random();
return (a+(b-a)*y);
}
public static void objective_function()
{
double x1,x2,x3;
int i;
for(i = 1; i <= POP_SIZE; i++)
{
x1 = CHROMOSOME[i][1];
x2 = CHROMOSOME[i][2];
x3 = CHROMOSOME[i][3];
OBJECTIVE[i][1] = Math.sqrt(x1)+Math.sqrt(x2)+Math.sqrt(x3);
}
for(i=1;i<=POP_SIZE;i++)
OBJECTIVE[i][0] = OBJECTIVE[i][1];
}
///////////////////////////
public static int constraint_check(double x[])
{
double a;
int n;
for(n=1;n<=N;n++)
if(x[n]<0)
return 0;
a = x[1]*x[1]+2*x[2]*x[2]+3*x[3]*x[3];
if(a>1)
return 0;
return 1;
}
/////////////////////////////////////////
public static void initialization()
{
double []x=new double [N+1]; // N is the number of variables
int i,j;
for(i=1; i<=POP_SIZE; i++)
{
do{
for(j=1; j<=N; j++)
x[j]=myu(0,1);}
while (constraint_check(x) == 0);
for(j=1; j<=N; j++)
CHROMOSOME[i][j]=x[j];
}
}
//////////////////////
public static void main(String arc[])
{
int i, j;
double a;
q[0]=0.05;
a=0.05;
for(i=1; i<=POP_SIZE; i++)
{
a=a*0.95;
q[i]=q[i-1]+a;
}
//q[]为seletion()函数中随机选择染色体做准备
initialization();
evaluation(0);
java.text.NumberFormat formater = java.text.DecimalFormat.getInstance();
formater.setMaximumFractionDigits(4);
for(i=1; i<=GEN; i++)
{
selection();
crossover();
mutation();
evaluation(i);
System.out.print("Generation NO.");
System.out.println(i);
//System.out.println("x=(");
for(j=1; j<=N; j++)
{
if(j<N)
System.out.println(formater.format(CHROMOSOME[0][j]));
else
System.out.println(formater.format(CHROMOSOME[0][j]));
}
if(M==1)
System.out.println(formater.format(OBJECTIVE[0][1]));
else
{
System.out.println(")\nf=(");
for(j=1; j<=M; j++)
{
if(j<M)
System.out.println(formater.format(OBJECTIVE[0][j]));
else
System.out.println(formater.format(OBJECTIVE[0][j]));
}
System.out.println(") Aggregating Value=%3.4f\n" + OBJECTIVE[0][0]);
}
}
System.out.println("\n");
// return 1;
}
//将染色体和目标函数按目标函数值由大到小进行排序
public static void evaluation(int gen)
{
double a;
int i, j, k, label;
objective_function();
if(gen==0)
{
for(k=0; k<=M; k++)
OBJECTIVE[0][k]=OBJECTIVE[1][k];
for(j = 1; j <= N; j++)
CHROMOSOME[0][j]=CHROMOSOME[1][j];
}
for(i=0; i<POP_SIZE; i++)
{
label=0;
a=OBJECTIVE[i][0];
for(j=i+1; j<=POP_SIZE; j++)
if((TYPE*a)<(TYPE*OBJECTIVE[j][0]))
{
a=OBJECTIVE[j][0];
label=j;
}
if(label!=0)
{
for(k=0; k<=M; k++)
{
a=OBJECTIVE[i][k];
OBJECTIVE[i][k]=OBJECTIVE[label][k];
OBJECTIVE[label][k]=a;
}
for(j=1; j<=N; j++)
{
a=CHROMOSOME[i][j];
CHROMOSOME[i][j]=CHROMOSOME[label][j];
CHROMOSOME[label][j]=a;
}
}
}
}
//////////////////////////////////////////
public static void selection()
{
double r;
double [][] temp=new double[POP_SIZE+1][N+1];
int i, j, k;
for(i=1; i<=POP_SIZE; i++)
{
r = myu(0,q[POP_SIZE]);
for(j=0; j<=POP_SIZE; j++)
{
if(r<=q[j])
{
for(k=1; k<=N; k++)
temp[i][k]=CHROMOSOME[j][k];
break;
}
}
}
for(i=1; i<=POP_SIZE; i++)
for(k=1; k<=N; k++)
CHROMOSOME[i][k]=temp[i][k];
}
///////////////////// 交配 //////////////////////
public static void crossover()
{
int i, j, jj, k, pop;
double r;
double[] x = new double[N+1];
double[] y = new double[N+1];
pop=POP_SIZE/2;
for(i=1; i<=pop; i++)
{
if(myu(0,1)>P_CROSSOVER)
continue;
j=(int)myu(1,POP_SIZE);
jj=(int)myu(1,POP_SIZE);
r=myu(0,1);
for(k=1; k<=N; k++)
{
x[k]=r*CHROMOSOME[j][k]+(1-r)*CHROMOSOME[jj][k];
y[k]=r*CHROMOSOME[jj][k]+(1-r)*CHROMOSOME[j][k];
}
if(constraint_check(x)==1)
for(k=1; k<=N; k++)
CHROMOSOME[j][k]=x[k];
if(constraint_check(y)==1)
for(k=1; k<=N; k++)
CHROMOSOME[jj][k]=y[k];
}
}
//////////////////////////////////////////
public static void mutation()
{
int i, j, k;
double infty;
double[] x = new double[N+1];
double[] y = new double[N+1];
double[] direction = new double[N+1];
double INFTY=10, precision=0.0001;
for(i=1; i<=POP_SIZE; i++)
{
if(myu(0,1)>P_MUTATION)
continue;
for(k=1; k<=N; k++)
x[k] = CHROMOSOME[i][k];
for(k=1; k<=N; k++)
if(myu(0,1)<0.5)
direction[k]=myu(-1,1);
else
direction[k]=0;
infty=myu(0,INFTY);
while(infty>precision)
{
for(j=1; j<=N; j++)
y[j]=x[j]+infty*direction[j];
if(constraint_check(y)==1)
{
for(k=1; k<=N; k++)
CHROMOSOME[i][k]=y[k];
break;
}
infty=myu(0,infty);
}
}
}
}
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