com.expleague.ml.loss.SatL2 Maven / Gradle / Ivy

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Various ML methods implemented by myself and my students

There is a newer version: 1.4.9

package com.expleague.ml.loss;

import com.expleague.commons.math.vectors.Vec;
import com.expleague.ml.data.set.DataSet;

/**
 * User: solar
 * Date: 21.12.2010
 * Time: 22:37:55
 */
public class SatL2 extends L2 {
  public SatL2(final Vec target, final DataSet base) {
    super(target, base);
  }

  @Override
  public double bestIncrement(final Stat stats) {
    return stats.weight > 2 ? stats.sum/stats.weight : 0;
  }

  @Override
  public double score(final Stat stats) {
    final double n = stats.weight;
    return n > 2 ? n*(n-2)/(n * n - 3 * n + 1) * (stats.sum2 - stats.sum * stats.sum / n) : stats.sum2;
  }
}