samoa-api/src/main/java/com/yahoo/labs/samoa/moa/classifiers/core/splitcriteria/SplitCriterion.java

package com.yahoo.labs.samoa.moa.classifiers.core.splitcriteria;

/*
 * #%L
 * SAMOA
 * %%
 *    Copyright (C) 2007 University of Waikato, Hamilton, New Zealand
 * %%
 * Licensed 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.
 * #L%
 */

import com.yahoo.labs.samoa.moa.options.OptionHandler;

/**
 * Interface for computing splitting criteria. with respect to distributions of
 * class values. The split criterion is used as a parameter on decision trees
 * and decision stumps. The two split criteria most used are Information Gain
 * and Gini.
 * 
 * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 * @version $Revision: 7 $
 */
public interface SplitCriterion extends OptionHandler {

  /**
   * Computes the merit of splitting for a given ditribution before the split
   * and after it.
   * 
   * @param preSplitDist
   *          the class distribution before the split
   * @param postSplitDists
   *          the class distribution after the split
   * @return value of the merit of splitting
   */
  public double getMeritOfSplit(double[] preSplitDist,
      double[][] postSplitDists);

  /**
   * Computes the range of splitting merit
   * 
   * @param preSplitDist
   *          the class distribution before the split
   * @return value of the range of splitting merit
   */
  public double getRangeOfMerit(double[] preSplitDist);
}