samoa-api/src/main/java/org/apache/samoa/moa/classifiers/rules/core/splitcriteria/SDRSplitCriterionAMRules.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
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package org.apache.samoa.moa.classifiers.rules.core.splitcriteria;

import org.apache.samoa.moa.classifiers.core.splitcriteria.SDRSplitCriterion;
import org.apache.samoa.moa.classifiers.core.splitcriteria.SplitCriterion;

public class SDRSplitCriterionAMRules extends SDRSplitCriterion implements SplitCriterion {

  private static final long serialVersionUID = 1L;

  @Override
  public double getMeritOfSplit(double[] preSplitDist, double[][] postSplitDists) {
    double SDR = 0.0;
    double N = preSplitDist[0];
    int count = 0;

    for (int i = 0; i < postSplitDists.length; i++)
    {
      double Ni = postSplitDists[i][0];
      if (Ni >= 0.05 * preSplitDist[0]) {
        count = count + 1;
      }
    }
    if (count == postSplitDists.length) {
      SDR = computeSD(preSplitDist);

      for (int i = 0; i < postSplitDists.length; i++)
      {
        double Ni = postSplitDists[i][0];
        SDR -= (Ni / N) * computeSD(postSplitDists[i]);

      }
    }
    return SDR;
  }

  @Override
  public double getRangeOfMerit(double[] preSplitDist) {
    return 1;
  }

  public static double[] computeBranchSplitMerits(double[][] postSplitDists) {
    double[] SDR = new double[postSplitDists.length];
    double N = 0;

    for (int i = 0; i < postSplitDists.length; i++)
    {
      double Ni = postSplitDists[i][0];
      N += Ni;
    }
    for (int i = 0; i < postSplitDists.length; i++)
    {
      double Ni = postSplitDists[i][0];
      SDR[i] = (Ni / N) * computeSD(postSplitDists[i]);
    }
    return SDR;

  }

}