relativeerrorfitness.java

是zuojie用java实现的gep库

package gep.num;


/**
 * 使用相对误差的适应度函数
 */
public class RelativeErrorFitness extends GeneralNFitness
{
	private final double MIN_FITNESS = 1.0;
	private double M;				// 允许的最大相对误差上限

	public RelativeErrorFitness(NDataSet dataSet, double M)
	{
		super(dataSet);
		this.M = M;
	}

	public double calculate(double[] values)
	{
		int size = targets.length;
		double fitness = 0.0;
		for (int i=0; i<size; i++)
		{
			fitness += M - Math.abs((values[i]-targets[i])/targets[i]*100);
		}
		if (fitness<MIN_FITNESS) fitness = MIN_FITNESS;

		return fitness;
	}

	public double getMinFitness()
	{
		return MIN_FITNESS;
	}
	
	public String toString()
	{
		return getClass().getName() + "(M:" + M +")";
	}
}