logitboost.java

Java 编写的多种数据挖掘算法 包括聚类、分类、预处理等

    if (numFolds.length() != 0) {
      setNumFolds(Integer.parseInt(numFolds));
    } else {
      setNumFolds(0);
    }
    
    String numRuns = Utils.getOption('R', options);
    if (numRuns.length() != 0) {
      setNumRuns(Integer.parseInt(numRuns));
    } else {
      setNumRuns(1);
    }

    String thresholdString = Utils.getOption('P', options);
    if (thresholdString.length() != 0) {
      setWeightThreshold(Integer.parseInt(thresholdString));
    } else {
      setWeightThreshold(100);
    }

    String precisionString = Utils.getOption('L', options);
    if (precisionString.length() != 0) {
      setLikelihoodThreshold(new Double(precisionString).
	doubleValue());
    } else {
      setLikelihoodThreshold(-Double.MAX_VALUE);
    }

    String shrinkageString = Utils.getOption('H', options);
    if (shrinkageString.length() != 0) {
      setShrinkage(new Double(shrinkageString).
	doubleValue());
    } else {
      setShrinkage(1.0);
    }

    setUseResampling(Utils.getFlag('Q', options));
    if (m_UseResampling && (thresholdString.length() != 0)) {
      throw new Exception("Weight pruning with resampling"+
			  "not allowed.");
    }

    super.setOptions(options);
  }

  /**
   * Gets the current settings of the Classifier.
   *
   * @return an array of strings suitable for passing to setOptions
   */
  public String [] getOptions() {

    String [] superOptions = super.getOptions();
    String [] options = new String [superOptions.length + 10];

    int current = 0;
    if (getUseResampling()) {
      options[current++] = "-Q";
    } else {
      options[current++] = "-P"; 
      options[current++] = "" + getWeightThreshold();
    }
    options[current++] = "-F"; options[current++] = "" + getNumFolds();
    options[current++] = "-R"; options[current++] = "" + getNumRuns();
    options[current++] = "-L"; options[current++] = "" + getLikelihoodThreshold();
    options[current++] = "-H"; options[current++] = "" + getShrinkage();

    System.arraycopy(superOptions, 0, options, current, 
		     superOptions.length);
    current += superOptions.length;
    while (current < options.length) {
      options[current++] = "";
    }
    return options;
  }
  
  /**
   * Returns the tip text for this property
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String shrinkageTipText() {
    return "Shrinkage parameter (use small value like 0.1 to reduce "
      + "overfitting).";
  }
			 
  /**
   * Get the value of Shrinkage.
   *
   * @return Value of Shrinkage.
   */
  public double getShrinkage() {
    
    return m_Shrinkage;
  }
  
  /**
   * Set the value of Shrinkage.
   *
   * @param newShrinkage Value to assign to Shrinkage.
   */
  public void setShrinkage(double newShrinkage) {
    
    m_Shrinkage = newShrinkage;
  }
  
  /**
   * Returns the tip text for this property
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String likelihoodThresholdTipText() {
    return "Threshold on improvement in likelihood.";
  }
			 
  /**
   * Get the value of Precision.
   *
   * @return Value of Precision.
   */
  public double getLikelihoodThreshold() {
    
    return m_Precision;
  }
  
  /**
   * Set the value of Precision.
   *
   * @param newPrecision Value to assign to Precision.
   */
  public void setLikelihoodThreshold(double newPrecision) {
    
    m_Precision = newPrecision;
  }
  
  /**
   * Returns the tip text for this property
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String numRunsTipText() {
    return "Number of runs for internal cross-validation.";
  }
  
  /**
   * Get the value of NumRuns.
   *
   * @return Value of NumRuns.
   */
  public int getNumRuns() {
    
    return m_NumRuns;
  }
  
  /**
   * Set the value of NumRuns.
   *
   * @param newNumRuns Value to assign to NumRuns.
   */
  public void setNumRuns(int newNumRuns) {
    
    m_NumRuns = newNumRuns;
  }
  
  /**
   * Returns the tip text for this property
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String numFoldsTipText() {
    return "Number of folds for internal cross-validation (default 0 "
      + "means no cross-validation is performed).";
  }
  
  /**
   * Get the value of NumFolds.
   *
   * @return Value of NumFolds.
   */
  public int getNumFolds() {
    
    return m_NumFolds;
  }
  
  /**
   * Set the value of NumFolds.
   *
   * @param newNumFolds Value to assign to NumFolds.
   */
  public void setNumFolds(int newNumFolds) {
    
    m_NumFolds = newNumFolds;
  }
  
  /**
   * Returns the tip text for this property
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String useResamplingTipText() {
    return "Whether resampling is used instead of reweighting.";
  }
  
  /**
   * Set resampling mode
   *
   * @param r true if resampling should be done
   */
  public void setUseResampling(boolean r) {
    
    m_UseResampling = r;
  }

  /**
   * Get whether resampling is turned on
   *
   * @return true if resampling output is on
   */
  public boolean getUseResampling() {
    
    return m_UseResampling;
  }
  
  /**
   * Returns the tip text for this property
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String weightThresholdTipText() {
    return "Weight threshold for weight pruning (reduce to 90 "
      + "for speeding up learning process).";
  }

  /**
   * Set weight thresholding
   *
   * @param threshold the percentage of weight mass used for training
   */
  public void setWeightThreshold(int threshold) {

    m_WeightThreshold = threshold;
  }

  /**
   * Get the degree of weight thresholding
   *
   * @return the percentage of weight mass used for training
   */
  public int getWeightThreshold() {

    return m_WeightThreshold;
  }

  /**
   * Returns default capabilities of the classifier.
   *
   * @return      the capabilities of this classifier
   */
  public Capabilities getCapabilities() {
    Capabilities result = super.getCapabilities();

    // class
    result.disableAllClasses();
    result.disableAllClassDependencies();
    result.enable(Capability.NOMINAL_CLASS);
    
    return result;
  }

  /**
   * Builds the boosted classifier
   * 
   * @param data the data to train the classifier with
   * @throws Exception if building fails, e.g., can't handle data
   */
  public void buildClassifier(Instances data) throws Exception {

    m_RandomInstance = new Random(m_Seed);
    int classIndex = data.classIndex();

    if (m_Classifier == null) {
      throw new Exception("A base classifier has not been specified!");
    }
    
    if (!(m_Classifier instanceof WeightedInstancesHandler) &&
	!m_UseResampling) {
      m_UseResampling = true;
    }

    // can classifier handle the data?
    getCapabilities().testWithFail(data);

    if (m_Debug) {
      System.err.println("Creating copy of the training data");
    }

    // remove instances with missing class
    data = new Instances(data);
    data.deleteWithMissingClass();
    
    m_NumClasses = data.numClasses();
    m_ClassAttribute = data.classAttribute();

    // Create the base classifiers
    if (m_Debug) {
      System.err.println("Creating base classifiers");
    }
    m_Classifiers = new Classifier [m_NumClasses][];
    for (int j = 0; j < m_NumClasses; j++) {
      m_Classifiers[j] = Classifier.makeCopies(m_Classifier,
					       getNumIterations());
    }

    // Do we want to select the appropriate number of iterations
    // using cross-validation?
    int bestNumIterations = getNumIterations();
    if (m_NumFolds > 1) {
      if (m_Debug) {
	System.err.println("Processing first fold.");
      }

      // Array for storing the results
      double[] results = new double[getNumIterations()];

      // Iterate throught the cv-runs
      for (int r = 0; r < m_NumRuns; r++) {

	// Stratify the data
	data.randomize(m_RandomInstance);
	data.stratify(m_NumFolds);
	
	// Perform the cross-validation
	for (int i = 0; i < m_NumFolds; i++) {
	  
	  // Get train and test folds
	  Instances train = data.trainCV(m_NumFolds, i, m_RandomInstance);
	  Instances test = data.testCV(m_NumFolds, i);
	  
	  // Make class numeric
	  Instances trainN = new Instances(train);
	  trainN.setClassIndex(-1);
	  trainN.deleteAttributeAt(classIndex);
	  trainN.insertAttributeAt(new Attribute("'pseudo class'"), classIndex);
	  trainN.setClassIndex(classIndex);
	  m_NumericClassData = new Instances(trainN, 0);
	  
	  // Get class values
	  int numInstances = train.numInstances();
	  double [][] trainFs = new double [numInstances][m_NumClasses];
	  double [][] trainYs = new double [numInstances][m_NumClasses];
	  for (int j = 0; j < m_NumClasses; j++) {
	    for (int k = 0; k < numInstances; k++) {
	      trainYs[k][j] = (train.instance(k).classValue() == j) ? 
		1.0 - m_Offset: 0.0 + (m_Offset / (double)m_NumClasses);
	    }
	  }
	  
	  // Perform iterations
	  double[][] probs = initialProbs(numInstances);
	  m_NumGenerated = 0;
	  double sumOfWeights = train.sumOfWeights();
	  for (int j = 0; j < getNumIterations(); j++) {
	    performIteration(trainYs, trainFs, probs, trainN, sumOfWeights);
	    Evaluation eval = new Evaluation(train);
	    eval.evaluateModel(this, test);
	    results[j] += eval.correct();
	  }
	}
      }
      
      // Find the number of iterations with the lowest error
      double bestResult = -Double.MAX_VALUE;
      for (int j = 0; j < getNumIterations(); j++) {
	if (results[j] > bestResult) {
	  bestResult = results[j];
	  bestNumIterations = j;
	}
      }
      if (m_Debug) {