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.
   */
  
  /*
   *    Kernel.java
   *    Copyright (C) 1999 University of Waikato, Hamilton, New Zealand
   *
   */
  
  package weka.classifiers.functions.supportVector;
  
  import weka.core.Capabilities;
  import weka.core.CapabilitiesHandler;
  import weka.core.Instance;
  import weka.core.Instances;
  import weka.core.Option;
  import weka.core.OptionHandler;
  import weka.core.RevisionHandler;
  import weka.core.RevisionUtils;
  import weka.core.SerializedObject;
  import weka.core.Utils;
  
  import java.io.Serializable;
  import java.util.Enumeration;
  import java.util.Vector;
  
  /**
   * Abstract kernel. 
   * Kernels implementing this class must respect Mercer's condition in order 
   * to ensure a correct behaviour of SMOreg.
   * 
   * @author Eibe Frank (eibe@cs.waikato.ac.nz)
   * @author FracPete (fracpete at waikato dot ac dot nz)
   * @version $Revision: 5449 $
   */
  public abstract class Kernel 
    implements Serializable, OptionHandler, CapabilitiesHandler, RevisionHandler {
  
    /** for serialization */
    private static final long serialVersionUID = -6102771099905817064L;
  
    /** The dataset */
    protected Instances m_data;
  
    /** enables debugging output */
    protected boolean m_Debug = false;
  
    /** Turns off all checks */
    protected boolean m_ChecksTurnedOff = false;
    
    /**
     * Returns a string describing the kernel
     * 
     * @return a description suitable for displaying in the
     *         explorer/experimenter gui
     */
    public abstract String globalInfo();
      
    /**
     * Computes the result of the kernel function for two instances.
     * If id1 == -1, eval use inst1 instead of an instance in the dataset.
     *
     * @param id1 the index of the first instance in the dataset
     * @param id2 the index of the second instance in the dataset
     * @param inst1 the instance corresponding to id1 (used if id1 == -1)
     * @return the result of the kernel function
     * @throws Exception if something goes wrong
     */
    public abstract double eval(int id1, int id2, Instance inst1) 
      throws Exception;
  
    /**
     * Frees the memory used by the kernel.
     * (Useful with kernels which use cache.)
     * This function is called when the training is done.
     * i.e. after that, eval will be called with id1 == -1.
     */
    public abstract void clean();
  
    /**
     * Returns the number of kernel evaluation performed.
     *
     * @return the number of kernel evaluation performed.
     */
    public abstract int numEvals();
  
    /**
     * Returns the number of dot product cache hits.
     *
     * @return the number of dot product cache hits, or -1 if not supported by this kernel.
     */
    public abstract int numCacheHits();
      
    /**
     * Returns an enumeration describing the available options.
     *
     * @return an enumeration of all the available options.
     */
    public Enumeration listOptions() {
      Vector		result;
      
      result = new Vector();
  
      result.addElement(new Option(
  	"\tEnables debugging output (if available) to be printed.\n"
  	+ "\t(default: off)",
  	"D", 0, "-D"));
  
      result.addElement(new Option(
  	"\tTurns off all checks - use with caution!\n"
  	+ "\t(default: checks on)",
  	"no-checks", 0, "-no-checks"));
  
      return result.elements();
    }
  
    /**
     * Parses a given list of options. <p/>
     * 
     * @param options the list of options as an array of strings
     * @throws Exception if an option is not supported
     */
    public void setOptions(String[] options) throws Exception {
      setDebug(Utils.getFlag('D', options));
  
      setChecksTurnedOff(Utils.getFlag("no-checks", options));
  
      Utils.checkForRemainingOptions(options);
    }
  
    /**
     * Gets the current settings of the Kernel.
     *
     * @return an array of strings suitable for passing to setOptions
     */
    public String[] getOptions() {
      Vector    result;
  
      result = new Vector();
  
      if (getDebug())
        result.add("-D");
  
      if (getChecksTurnedOff())
        result.add("-no-checks");
  
      return (String[]) result.toArray(new String[result.size()]);	  
    }
  
    /**
     * Enables or disables the output of debug information (if the derived
     * kernel supports that)
     * 
     * @param value	whether to output debugging information
     */
    public void setDebug(boolean value) {
      m_Debug = value;
    }
    
    /**
     * Gets whether debugging output is turned on or not.
     * 
     * @return		true if debugging output is produced.
     */
    public boolean getDebug() {
      return m_Debug;
    }
  
    /**
     * Returns the tip text for this property
     * 
     * @return 		tip text for this property suitable for
     * 			displaying in the explorer/experimenter gui
     */
    public String debugTipText() {
      return "Turns on the output of debugging information.";
    }
    
    /**
     * Disables or enables the checks (which could be time-consuming). Use with
     * caution!
     * 
     * @param value	if true turns off all checks
     */
    public void setChecksTurnedOff(boolean value) {
      m_ChecksTurnedOff = value;
    }
    
    /**
     * Returns whether the checks are turned off or not.
     * 
     * @return		true if the checks are turned off
     */
    public boolean getChecksTurnedOff() {
      return m_ChecksTurnedOff;
    }
  
    /**
     * Returns the tip text for this property
     * 
     * @return 		tip text for this property suitable for
     * 			displaying in the explorer/experimenter gui
     */
    public String checksTurnedOffTipText() {
      return "Turns time-consuming checks off - use with caution.";
    }
    
    /**
     * initializes variables etc.
     * 
     * @param data	the data to use
     */
    protected void initVars(Instances data) {
      m_data = data;
    }
  
    /** 
     * Returns the Capabilities of this kernel. Derived kernels have to
     * override this method to enable capabilities.
     *
     * @return            the capabilities of this object
     * @see               Capabilities
     */
    public Capabilities getCapabilities() {
      Capabilities result = new Capabilities(this);
      result.enableAll();
      
      return result;
    }
    
    /**
     * Returns the revision string.
     * 
     * @return            the revision
     */
    public String getRevision() {
      return RevisionUtils.extract("$Revision: 5449 $");
    }
    
    /**
     * builds the kernel with the given data
     * 
     * @param data	the data to base the kernel on
     * @throws Exception	if something goes wrong
     */
    public void buildKernel(Instances data) throws Exception {
      // does kernel handle the data?
      if (!getChecksTurnedOff())
        getCapabilities().testWithFail(data);
      
      initVars(data);
    }
  
    /**
     * Creates a deep copy of the given kernel using serialization.
     *
     * @param kernel 	the kernel to copy
     * @return 		a deep copy of the kernel
     * @throws Exception 	if an error occurs
     */
    public static Kernel makeCopy(Kernel kernel) throws Exception {
      return (Kernel) new SerializedObject(kernel).getObject();
    }
  
    /**
     * Creates a given number of deep copies of the given kernel using 
     * serialization.
     * 
     * @param model 	the kernel to copy
     * @param num 	the number of kernel copies to create.
     * @return 		an array of kernels.
     * @throws Exception 	if an error occurs
     */
    public static Kernel[] makeCopies(Kernel model, int num) throws Exception {
      if (model == null)
        throw new Exception("No model kernel set");
  
      Kernel[] kernels = new Kernel[num];
      SerializedObject so = new SerializedObject(model);
      for (int i = 0; i < kernels.length; i++)
        kernels[i] = (Kernel) so.getObject();
  
      return kernels;
    }
    
    /**
     * Creates a new instance of a kernel given it's class name and
     * (optional) arguments to pass to it's setOptions method.
     *
     * @param kernelName 	the fully qualified class name of the classifier
     * @param options 	an array of options suitable for passing to setOptions. May
     * 			be null.
     * @return 		the newly created classifier, ready for use.
     * @throws Exception 	if the classifier name is invalid, or the options
     * 			supplied are not acceptable to the classifier
     */
    public static Kernel forName(String kernelName, String[] options) 
      throws Exception {
  
      return (Kernel) Utils.forName(Kernel.class, kernelName, options);
    }
  }
  