/** 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++;
}
}
/**
* 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();
}
/**
* 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);
}
}
/**
* 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;
}
}
/**
* 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();
}
}
