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package com.shijingsh.ai.evaluate.rating;

import java.util.Iterator;

import com.shijingsh.ai.evaluate.RatingEvaluator;

import com.shijingsh.ai.evaluate.RatingEvaluator;
import it.unimi.dsi.fastutil.floats.FloatList;

/**
 * 平均相对误差评估器
 *
 *  * MPE = Mean Prediction  Error
 * 
 *
 * @author Birdy
 */
public class MPEEvaluator extends RatingEvaluator {

    private float mpe;

    public MPEEvaluator(float minimum, float maximum, float mpe) {
        super(minimum, maximum);
        this.mpe = mpe;
    }

    @Override
    protected float measure(FloatList checkCollection, FloatList rateList) {
        float value = 0F;
        Iterator iterator = checkCollection.iterator();
        for (float estimate : rateList) {
            float score = iterator.next();
            if (estimate > maximum) {
                estimate = maximum;
            }
            if (estimate < minimum) {
                estimate = minimum;
            }
            if (Math.abs(score - estimate) > mpe) {
                value++;
            }
        }
        return value;
    }

}