これが私の問題です。遺伝的アルゴリズム用に見つけたコードを変更して、関数の数値最適化を実行しています。基本的に、関数Fと目的の値が与えられると、プログラムはGAを使用して、適切な目的の値を提供するxとyの値を検索します。私は自分のフィットネス機能をいじくり回し続けていますが、それが問題の根源だと感じています。
基本的なコードの内訳は次のとおりです。
ランダムな染色体集団を生成する
各染色体の適合性に基づいてバブルソートを使用する
それらのいずれかが機能を解決するために起こったかどうかを確認してください
解決したら、停止して印刷します
それ以外の場合は、親に基づいて子を生成します並べ替え、ベストアンサーを確認し、ループします
誰かが私を正しい方向に向けてくれることを願っています。私は今夜もう一度それを分析するつもりですが、私はこれにひっかかったようです。私がハードコーディングしたものよりも複雑な関数の場合、ランダムなパーセンテージ（通常は20未満）で収束するようです...しかし、0にはるかに近いはずです。単純なコーディングされた関数は約99％の差を返し続けます...だから私は何が起こっているのか100％ではありません。
import java.util.*;
import java.util.Comparator;
import java.util.TreeMap;
/**
* Modified from a file created Jul 9, 2003
* Original @author Fabian Jones
* Modified @author Cutright
* @version 2
*/
public class ScratchGA
{
private static int NUM_CHROMOSOMES = 100; //num of chromosomes in population
private static double MUTATE = .01; //chance of a mutation i.e. 88.8%
private static int desiredValue = 60466176; //desired value of function
private static int cutoff = 1000; // number of iterations before cut off
private static int longPrint = 0; //1 means print out each iteration of the population
private boolean done = false;
private Chromosome[] population;
int iteration = 0;
/**
* Constructor for objects of class ScratchGA
*/
public ScratchGA()
{
generateRandomPopulation(NUM_CHROMOSOMES);
printPopulation();
}
/**
* Generate a random population of chromosomes - WORKS
*
*/
private void generateRandomPopulation(int pop)
{
System.out.println("Generating random population of " + pop + ", now." +"\n");
population = new Chromosome[pop];
for(int i=0; i<pop; i++)
{
int rand = (int)(Math.random()*4095); // Range 0 to 4095
population[i] = (new Chromosome(rand, 12));
}
}
/**
* Codesaver for generating a new line in the output
*/
private void newLine()
{
System.out.println("\n");
}
/**
* Prints the population (the chromosomes)
*/
private void printPopulation()
{
int x=1; // variable to print 10 chromosomes on a line
if (iteration==0)
{
System.out.println("Initial population: " + "\n" );
}
else
{
if (longPrint ==1)
{
System.out.println("Population " + iteration + " :" + "\n");
for(int i=0; i<=(NUM_CHROMOSOMES-1); i++)
{
System.out.print(population[i] + " ");
if(x == 10)
{
newLine();
x=1;
}
else
{
x++;
}
}
newLine();
}
else
{
System.out.println("Best answer for iteration " + iteration + " is: " + population[0] + " with a % difference of " +population[0].getFitness());
newLine();
}
}
}
/**
* Start
* Bubblesort initial population by their fitness, see if the first chromosome
* in the sorted array satisfies our constraint.
* IF done ==true or max num of iterations
* Print best solution and its fitness
* ELSE
* generate new population based on old one, and continue on
*/
public void start()
{
// System.out.println("Starting bubblesort... Please Wait.");
bubbleSort();
//System.out.println("After Bubblesort: " );
//printPopulation();
topFitness();
if(done || iteration==cutoff){
System.out.println("DONE!!");
System.out.println("Best solution: " + population[0] + " % Difference: " + population[0].getFitness());
}
else{
iteration++;
generateNewPopulation();
printPopulation();
start();
}
}
/**
* If the top chromosomes fitness (after being sorted by bubblesort) is 100%
* done == true
*/
private void topFitness()
{
if (population[0].getFitness() == 0)
{
done = true;
}
}
/**
* Called from chromosome,
* Tests the x and y values in the function and returns their output
*/
public static double functionTest(int x, int y)
{
return (3*x)^(2*y); // From our desired value we're looking for x=2, y=5
}
/**
* Returns the desired outcome of the function, with ideal x and y
* Stored above in a private static
*/
public static int getDesired()
{
return desiredValue;
}
/**
* Sort Chromosome array, based on fitness
* utilizes a bubblesort
*/
private void bubbleSort()
{
Chromosome temp;
for(int i=0; i<NUM_CHROMOSOMES; i++){
for(int j=1; j<(NUM_CHROMOSOMES-i); j++){
if(population[j-1].getFitness() > population[j].getFitness())
{
//swap elements
temp = population[j-1];
population[j-1] = population[j];
population[j] = temp;
}
}
}
}
/**
* Top 30: Elitism
* Next 60: Offspring of Elitists
* Next 10: Random
*/
private void generateNewPopulation(){
System.out.println("***Generating New Population");
Chromosome[] temp = new Chromosome[100];
for (int i = 0; i < 30; i++)
{
Chromosome x = population[i];
if (shouldMutate())
mutate(x);
temp[i]=x;
}
for (int i = 0; i < 30; i++)
{
temp[i+30] =cross1(population[i], population[i+1]);
temp[i+60] = cross2(population[i], population[i+1]);
}
for (int i = 90; i<100; i++)
{
int rand = (int)(Math.random()*4095); // Range 0 to 4095
Chromosome x = new Chromosome(rand, 12);
temp[i] = x;
}
population = temp;
}
/**
* First cross type, with two parents
*/
private Chromosome cross1(Chromosome parent1, Chromosome parent2){
String bitS1 = parent1.getBitString();
String bitS2 = parent2.getBitString();
int length = bitS1.length();
int num = (int)(Math.random()*length); // number from 0 to length-1
String newBitString = bitS2.substring(0, num) + bitS1.substring(num, length);
Chromosome offspring = new Chromosome();
offspring.setBitString(newBitString);
if(shouldMutate()){
mutate(offspring);
}
return offspring;
}
/**
* Second cross type, parents given in same order as first, but reverses internal workings
*/
private Chromosome cross2(Chromosome parent1, Chromosome parent2){
String bitS1 = parent1.getBitString();
String bitS2 = parent2.getBitString();
int length = bitS1.length();
int num = (int)(Math.random()*length); // number from 0 to length-1
String newBitString = bitS2.substring(0, num) + bitS1.substring(num, length);
Chromosome offspring = new Chromosome();
offspring.setBitString(newBitString);
if(shouldMutate()){
mutate(offspring);
}
return offspring;
}
/**
* Returns a boolean of whether a character should mutate based on the mutation value at top
*/
private boolean shouldMutate(){
double num = Math.random()*100;
return (num <= MUTATE);
}
/**
* Returns a boolean of whether a character should mutate based on the mutation value at top
*/
private void mutate(Chromosome offspring){
String s = offspring.getBitString();
int num = s.length();
int index = (int) (Math.random()*num);
String newBit = flip(s.substring(index, index+1));
String newBitString = s.substring(0, index) + newBit + s.substring(index+1, s.length());
offspring.setBitString(newBitString);
}
/**
* Flips bits in a string 1 to 0, 0 to 1
*/
private String flip(String s){
return s.equals("0")? "1":"0";
}
}
import java.lang.Comparable;
import java.math.*;
/**
* Modified from a file created on Jul 9, 2003
* Unsure of original author
*
*/
public class Chromosome implements Comparable
{
protected String bitString;
/**
* Constructor for objects of class Chromosome
*/
public Chromosome()
{
}
public Chromosome(int value, int length)
{
bitString = convertIntToBitString(value, length);
}
public void setBitString(String s)
{
bitString = s;
}
public String getBitString()
{
return bitString;
}
public int compareTo(Object o)
{
Chromosome c = (Chromosome) o;
int num = countOnes(this.bitString) - countOnes(c.getBitString());
return num;
}
public double getFitness()
{
String working = bitString;
int x1 = Integer.parseInt(working.substring(0,6),2);
int x2 = Integer.parseInt(working.substring(6),2);
double result = ScratchGA.functionTest(x1,x2);
double percentDiff = ((ScratchGA.getDesired() - result)/ScratchGA.getDesired())*100;
if (percentDiff >= 0)
{
return percentDiff;
}
else
{
return -percentDiff;
}
}
public boolean equals(Object o)
{
if(o instanceof Chromosome)
{
Chromosome c = (Chromosome) o;
return c.getBitString().equals(bitString);
}
return false;
}
public int hashCode()
{
return bitString.hashCode();
}
public String toString()
{
return bitString;
}
public static int countOnes(String bits)
{
int sum = 0;
for(int i = 0; i < bits.length(); ++ i){
String test = bits.substring(i, i+1);
if(test.equals("1")){
sum = sum + 1;
}
}
return sum;
}
public static String convertIntToBitString(int val, int length)
{
int reval = val;
StringBuffer bitString = new StringBuffer(length);
for(int i = length-1; i >=0; --i ){
if( reval - (Math.pow(2, i)) >= 0 ){
bitString.append("1");
reval = (int) (reval - Math.pow(2, i));
}
else{
bitString.append("0");
}
}
return bitString.toString();
}
public static void main(String[] args
){
//System.out.println(convertIntToBitString(2046, 10));
Chromosome c = new Chromosome(1234, 10);
//System.out.println(c.fitness());
}
}