Associator.java

/*
 *    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.
 */

/*
 *    Associator.java
 *    Copyright (C) 1999 Eibe Frank
 *
 */

package weka.associations;

import java.io.Serializable;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.SerializedObject;
import weka.core.Utils;

/** 
 * Abstract scheme for learning associations. All schemes for learning
 * associations implemement this class
 *
 * @author Eibe Frank (eibe@cs.waikato.ac.nz)
 * @version $Revision: 1.1.1.1 $ 
 */
public abstract class Associator implements Cloneable, Serializable {
 
  /**
   * Generates an associator. Must initialize all fields of the associator
   * that are not being set via options (ie. multiple calls of buildAssociator
   * must always lead to the same result). Must not change the dataset
   * in any way.
   *
   * @param data set of instances serving as training data 
   * @exception Exception if the associator has not been 
   * generated successfully
   */
  public abstract void buildAssociations(Instances data) throws Exception;

  /**
   * Creates a new instance of a associator given it's class name and
   * (optional) arguments to pass to it's setOptions method. If the
   * associator implements OptionHandler and the options parameter is
   * non-null, the associator will have it's options set.
   *
   * @param associatorName the fully qualified class name of the associator
   * @param options an array of options suitable for passing to setOptions. May
   * be null.
   * @return the newly created associator, ready for use.
   * @exception Exception if the associator name is invalid, or the options
   * supplied are not acceptable to the associator
   */
  public static Associator forName(String associatorName,
				   String [] options) throws Exception {

    return (Associator)Utils.forName(Associator.class,
				     associatorName,
				     options);
  }

  /**
   * Creates copies of the current associator. Note that this method
   * now uses Serialization to perform a deep copy, so the Associator
   * object must be fully Serializable. Any currently built model will
   * now be copied as well.
   *
   * @param model an example associator to copy
   * @param num the number of associators copies to create.
   * @return an array of associators.
   * @exception Exception if an error occurs 
   */
  public static Associator [] makeCopies(Associator model,
					 int num) throws Exception {

    if (model == null) {
      throw new Exception("No model associator set");
    }
    Associator [] associators = new Associator [num];
    SerializedObject so = new SerializedObject(model);
    for(int i = 0; i < associators.length; i++) {
      associators[i] = (Associator) so.getObject();
    }
    return associators;
  }
}