示例#1
0
  /** Computes average class values for each attribute and value */
  private void computeAverageClassValues() {

    double totalCounts, sum;
    Instance instance;
    double[] counts;

    double[][] avgClassValues = new double[getInputFormat().numAttributes()][0];
    m_Indices = new int[getInputFormat().numAttributes()][0];
    for (int j = 0; j < getInputFormat().numAttributes(); j++) {
      Attribute att = getInputFormat().attribute(j);
      if (att.isNominal()) {
        avgClassValues[j] = new double[att.numValues()];
        counts = new double[att.numValues()];
        for (int i = 0; i < getInputFormat().numInstances(); i++) {
          instance = getInputFormat().instance(i);
          if (!instance.classIsMissing() && (!instance.isMissing(j))) {
            counts[(int) instance.value(j)] += instance.weight();
            avgClassValues[j][(int) instance.value(j)] += instance.weight() * instance.classValue();
          }
        }
        sum = Utils.sum(avgClassValues[j]);
        totalCounts = Utils.sum(counts);
        if (Utils.gr(totalCounts, 0)) {
          for (int k = 0; k < att.numValues(); k++) {
            if (Utils.gr(counts[k], 0)) {
              avgClassValues[j][k] /= counts[k];
            } else {
              avgClassValues[j][k] = sum / totalCounts;
            }
          }
        }
        m_Indices[j] = Utils.sort(avgClassValues[j]);
      }
    }
  }
  protected void updateClassifier(Instance instance, boolean updateDictionary) throws Exception {

    if (!instance.classIsMissing()) {
      int classIndex = (int) instance.classValue();
      m_probOfClass[classIndex] += instance.weight();

      tokenizeInstance(instance, updateDictionary);
      m_t++;
    }
  }
示例#3
0
  /**
   * Adds the supplied instance to the training set
   *
   * @param instance the instance to add
   * @throws Exception if instance could not be incorporated successfully
   */
  public void updateClassifier(Instance instance) throws Exception {
    String debug = "(KStar.updateClassifier) ";

    if (m_Train.equalHeaders(instance.dataset()) == false)
      throw new Exception("Incompatible instance types");
    if (instance.classIsMissing()) return;
    m_Train.add(instance);
    // update relevant attributes ...
    update_m_Attributes();
  }
示例#4
0
  /**
   * Adds the supplied instance to the training set.
   *
   * @param instance the instance to add
   * @throws Exception if instance could not be incorporated successfully
   */
  public void updateClassifier(Instance instance) throws Exception {

    if (m_Train == null) {
      throw new Exception("No training instance structure set!");
    } else if (m_Train.equalHeaders(instance.dataset()) == false) {
      throw new Exception(
          "Incompatible instance types\n" + m_Train.equalHeadersMsg(instance.dataset()));
    }
    if (!instance.classIsMissing()) {
      m_NNSearch.update(instance);
      m_Train.add(instance);
    }
  }
  /**
   * Adds the supplied instance to the training set.
   *
   * @param instance the instance to add
   * @throws Exception if instance could not be incorporated successfully
   */
  public void updateClassifier(Instance instance) throws Exception {

    if (m_Train.equalHeaders(instance.dataset()) == false) {
      throw new Exception("Incompatible instance types");
    }
    if (instance.classIsMissing()) {
      return;
    }

    m_Train.add(instance);
    m_NNSearch.update(instance);
    m_kNNValid = false;
    if ((m_WindowSize > 0) && (m_Train.numInstances() > m_WindowSize)) {
      boolean deletedInstance = false;
      while (m_Train.numInstances() > m_WindowSize) {
        m_Train.delete(0);
        deletedInstance = true;
      }
      // rebuild datastructure KDTree currently can't delete
      if (deletedInstance == true) m_NNSearch.setInstances(m_Train);
    }
  }
示例#6
0
  /**
   * Generates the classifier.
   *
   * @param instances set of instances serving as training data
   * @exception Exception if the classifier has not been generated successfully
   */
  @Override
  public void buildClassifier(Instances instances) throws Exception {

    int attIndex = 0;
    double sum;

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

    // remove instances with missing class
    instances = new Instances(instances);
    instances.deleteWithMissingClass();

    m_Instances = new Instances(instances, 0);

    // Reserve space
    m_Counts = new double[instances.numClasses()][instances.numAttributes() - 1][0];
    m_Means = new double[instances.numClasses()][instances.numAttributes() - 1];
    m_Devs = new double[instances.numClasses()][instances.numAttributes() - 1];
    m_Priors = new double[instances.numClasses()];
    Enumeration<Attribute> enu = instances.enumerateAttributes();
    while (enu.hasMoreElements()) {
      Attribute attribute = enu.nextElement();
      if (attribute.isNominal()) {
        for (int j = 0; j < instances.numClasses(); j++) {
          m_Counts[j][attIndex] = new double[attribute.numValues()];
        }
      } else {
        for (int j = 0; j < instances.numClasses(); j++) {
          m_Counts[j][attIndex] = new double[1];
        }
      }
      attIndex++;
    }

    // Compute counts and sums
    Enumeration<Instance> enumInsts = instances.enumerateInstances();
    while (enumInsts.hasMoreElements()) {
      Instance instance = enumInsts.nextElement();
      if (!instance.classIsMissing()) {
        Enumeration<Attribute> enumAtts = instances.enumerateAttributes();
        attIndex = 0;
        while (enumAtts.hasMoreElements()) {
          Attribute attribute = enumAtts.nextElement();
          if (!instance.isMissing(attribute)) {
            if (attribute.isNominal()) {
              m_Counts[(int) instance.classValue()][attIndex][(int) instance.value(attribute)]++;
            } else {
              m_Means[(int) instance.classValue()][attIndex] += instance.value(attribute);
              m_Counts[(int) instance.classValue()][attIndex][0]++;
            }
          }
          attIndex++;
        }
        m_Priors[(int) instance.classValue()]++;
      }
    }

    // Compute means
    Enumeration<Attribute> enumAtts = instances.enumerateAttributes();
    attIndex = 0;
    while (enumAtts.hasMoreElements()) {
      Attribute attribute = enumAtts.nextElement();
      if (attribute.isNumeric()) {
        for (int j = 0; j < instances.numClasses(); j++) {
          if (m_Counts[j][attIndex][0] < 2) {
            throw new Exception(
                "attribute "
                    + attribute.name()
                    + ": less than two values for class "
                    + instances.classAttribute().value(j));
          }
          m_Means[j][attIndex] /= m_Counts[j][attIndex][0];
        }
      }
      attIndex++;
    }

    // Compute standard deviations
    enumInsts = instances.enumerateInstances();
    while (enumInsts.hasMoreElements()) {
      Instance instance = enumInsts.nextElement();
      if (!instance.classIsMissing()) {
        enumAtts = instances.enumerateAttributes();
        attIndex = 0;
        while (enumAtts.hasMoreElements()) {
          Attribute attribute = enumAtts.nextElement();
          if (!instance.isMissing(attribute)) {
            if (attribute.isNumeric()) {
              m_Devs[(int) instance.classValue()][attIndex] +=
                  (m_Means[(int) instance.classValue()][attIndex] - instance.value(attribute))
                      * (m_Means[(int) instance.classValue()][attIndex]
                          - instance.value(attribute));
            }
          }
          attIndex++;
        }
      }
    }
    enumAtts = instances.enumerateAttributes();
    attIndex = 0;
    while (enumAtts.hasMoreElements()) {
      Attribute attribute = enumAtts.nextElement();
      if (attribute.isNumeric()) {
        for (int j = 0; j < instances.numClasses(); j++) {
          if (m_Devs[j][attIndex] <= 0) {
            throw new Exception(
                "attribute "
                    + attribute.name()
                    + ": standard deviation is 0 for class "
                    + instances.classAttribute().value(j));
          } else {
            m_Devs[j][attIndex] /= m_Counts[j][attIndex][0] - 1;
            m_Devs[j][attIndex] = Math.sqrt(m_Devs[j][attIndex]);
          }
        }
      }
      attIndex++;
    }

    // Normalize counts
    enumAtts = instances.enumerateAttributes();
    attIndex = 0;
    while (enumAtts.hasMoreElements()) {
      Attribute attribute = enumAtts.nextElement();
      if (attribute.isNominal()) {
        for (int j = 0; j < instances.numClasses(); j++) {
          sum = Utils.sum(m_Counts[j][attIndex]);
          for (int i = 0; i < attribute.numValues(); i++) {
            m_Counts[j][attIndex][i] =
                (m_Counts[j][attIndex][i] + 1) / (sum + attribute.numValues());
          }
        }
      }
      attIndex++;
    }

    // Normalize priors
    sum = Utils.sum(m_Priors);
    for (int j = 0; j < instances.numClasses(); j++) {
      m_Priors[j] = (m_Priors[j] + 1) / (sum + instances.numClasses());
    }
  }
  public void buildClassifier(Instances insts) throws Exception {

    // Compute mean of target value
    double yMean = insts.meanOrMode(insts.classIndex());

    // Choose best attribute
    double minMsq = Double.MAX_VALUE;
    m_attribute = null;
    int chosen = -1;
    double chosenSlope = Double.NaN;
    double chosenIntercept = Double.NaN;
    for (int i = 0; i < insts.numAttributes(); i++) {
      if (i != insts.classIndex()) {
        if (!insts.attribute(i).isNumeric()) {
          throw new Exception("UnivariateLinearRegression: Only numeric attributes!");
        }
        m_attribute = insts.attribute(i);

        // Compute slope and intercept
        double xMean = insts.meanOrMode(i);
        double sumWeightedXDiffSquared = 0;
        double sumWeightedYDiffSquared = 0;
        m_slope = 0;
        for (int j = 0; j < insts.numInstances(); j++) {
          Instance inst = insts.instance(j);
          if (!inst.isMissing(i) && !inst.classIsMissing()) {
            double xDiff = inst.value(i) - xMean;
            double yDiff = inst.classValue() - yMean;
            double weightedXDiff = inst.weight() * xDiff;
            double weightedYDiff = inst.weight() * yDiff;
            m_slope += weightedXDiff * yDiff;
            sumWeightedXDiffSquared += weightedXDiff * xDiff;
            sumWeightedYDiffSquared += weightedYDiff * yDiff;
          }
        }

        // Skip attribute if not useful
        if (sumWeightedXDiffSquared == 0) {
          continue;
        }
        double numerator = m_slope;
        m_slope /= sumWeightedXDiffSquared;
        m_intercept = yMean - m_slope * xMean;

        // Compute sum of squared errors
        double msq = sumWeightedYDiffSquared - m_slope * numerator;

        // Check whether this is the best attribute
        if (msq < minMsq) {
          minMsq = msq;
          chosen = i;
          chosenSlope = m_slope;
          chosenIntercept = m_intercept;
        }
      }
    }

    // Set parameters
    if (chosen == -1) {

      System.err.println("----- no useful attribute found");
      m_attribute = null;
      m_slope = 0;
      m_intercept = yMean;
    } else {
      m_attribute = insts.attribute(chosen);
      m_slope = chosenSlope;
      m_intercept = chosenIntercept;
    }
  }
示例#8
0
  /**
   * Updates all the statistics about a classifiers performance for the current test instance.
   *
   * @param predictedDistribution the probabilities assigned to each class
   * @param instance the instance to be classified
   * @throws Exception if the class of the instance is not set
   */
  protected void updateStatsForClassifier(double[] predictedDistribution, Instance instance)
      throws Exception {

    int actualClass = (int) instance.classValue();

    if (!instance.classIsMissing()) {
      updateMargins(predictedDistribution, actualClass, instance.weight());

      // collect all predictions and their corresponding classes
      SortedMap<Double, Integer> predToClass = new TreeMap<Double, Integer>(descendingDouble);
      for (int i = 0; i < m_NumClasses; i++) {
        predToClass.put(predictedDistribution[i], i);
      }
      List<Integer> candidateClasses = new ArrayList<Integer>(relaxParam);
      int count = 0;
      for (Double pred : predToClass.keySet()) {
        candidateClasses.add(predToClass.get(pred));
        count++;
        if (count == relaxParam) break;
      }
      // check if relaxed set of candidates contains actual, if so -
      // attribute that prediction
      // otherwise - take the to pprediction
      int predictedClass = -1;
      if (candidateClasses.contains(actualClass)) predictedClass = actualClass;
      else predictedClass = candidateClasses.get(0);

      /*
      // Determine the predicted class (doesn't detect multiple
      // classifications)
      int predictedClass = -1;
      double bestProb = 0.0;
      for(int i = 0; i < m_NumClasses; i++) {
      	if (predictedDistribution[i] > bestProb) {
      		predictedClass = i;
      		bestProb = predictedDistribution[i];
      	}
      }
       */

      m_WithClass += instance.weight();

      // Determine misclassification cost
      if (m_CostMatrix != null) {
        if (predictedClass < 0) {
          // For missing predictions, we assume the worst possible cost.
          // This is pretty harsh.
          // Perhaps we could take the negative of the cost of a correct
          // prediction (-m_CostMatrix.getElement(actualClass,actualClass)),
          // although often this will be zero
          m_TotalCost += instance.weight() * m_CostMatrix.getMaxCost(actualClass, instance);
        } else {
          m_TotalCost +=
              instance.weight() * m_CostMatrix.getElement(actualClass, predictedClass, instance);
        }
      }

      // Update counts when no class was predicted
      if (predictedClass < 0) {
        m_Unclassified += instance.weight();
        return;
      }

      double predictedProb = Math.max(MIN_SF_PROB, predictedDistribution[actualClass]);
      double priorProb = Math.max(MIN_SF_PROB, m_ClassPriors[actualClass] / m_ClassPriorsSum);
      if (predictedProb >= priorProb) {
        m_SumKBInfo += (Utils.log2(predictedProb) - Utils.log2(priorProb)) * instance.weight();
      } else {
        m_SumKBInfo -=
            (Utils.log2(1.0 - predictedProb) - Utils.log2(1.0 - priorProb)) * instance.weight();
      }

      m_SumSchemeEntropy -= Utils.log2(predictedProb) * instance.weight();
      m_SumPriorEntropy -= Utils.log2(priorProb) * instance.weight();

      updateNumericScores(
          predictedDistribution, makeDistribution(instance.classValue()), instance.weight());

      // Update other stats
      m_ConfusionMatrix[actualClass][predictedClass] += instance.weight();
      if (predictedClass != actualClass) {
        m_Incorrect += instance.weight();
      } else {
        m_Correct += instance.weight();
      }
    } else {
      m_MissingClass += instance.weight();
    }
  }