content: /*
   *    This program is free software; you can redistribute it and/or modify
   *    it under the terms of the GNU General Public License as published by
   *    the Free Software Foundation; either version 2 of the License, or
   *    (at your option) any later version.
   *
   *    This program is distributed in the hope that it will be useful,
   *    but WITHOUT ANY WARRANTY; without even the implied warranty of
   *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *    GNU General Public License for more details.
   *
   *    You should have received a copy of the GNU General Public License
   *    along with this program; if not, write to the Free Software
   *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  /*
   *    DensityBasedClusterer.java
   *    Copyright (C) 1999 University of Waikato, Hamilton, New Zealand
   *
   */
  
  package weka.clusterers;
  
  import weka.core.Instance;
  
  /**
   * Interface for clusterers that can estimate the density for a given instance.
   * Implementations will typically extend AbstractDensityBasedClusterer.
   *
   * @author   Mark Hall (mhall@cs.waikato.ac.nz)
   * @author Eibe Frank (eibe@cs.waikato.ac.nz)
   * @version  $Revision: 5987 $
   */
  public interface DensityBasedClusterer extends Clusterer {
  
    /**
     * Returns the prior probability of each cluster.
     *
     * @return the prior probability for each cluster
     * @exception Exception if priors could not be 
     * returned successfully
     */
    double[] clusterPriors() throws Exception;
  
    /**
     * Computes the log of the conditional density (per cluster) for a given instance.
     * 
     * @param instance the instance to compute the density for
     * @return an array containing the estimated densities
     * @exception Exception if the density could not be computed
     * successfully
     */
    double[] logDensityPerClusterForInstance(Instance instance) throws Exception;
  
    /**
     * Computes the density for a given instance.
     * 
     * @param instance the instance to compute the density for
     * @return the density.
     * @exception Exception if the density could not be computed successfully
     */
    double logDensityForInstance(Instance instance) throws Exception;
  
    /** 
     * Returns the logs of the joint densities for a given instance.
     *
     * @param inst the instance 
     * @return the array of values
     * @exception Exception if values could not be computed
     */
    double[] logJointDensitiesForInstance(Instance inst) throws Exception;
  }
  