/**
* Constructor that generates a sparse instance from the given instance. Reference to the dataset
* is set to null. (ie. the instance doesn't have access to information about the attribute types)
*
* @param instance the instance from which the attribute values and the weight are to be copied
*/
public SparseInstance(Instance instance) {
m_Weight = instance.weight();
m_Dataset = null;
m_NumAttributes = instance.numAttributes();
if (instance instanceof SparseInstance) {
m_AttValues = ((SparseInstance) instance).m_AttValues;
m_Indices = ((SparseInstance) instance).m_Indices;
} else {
double[] tempValues = new double[instance.numAttributes()];
int[] tempIndices = new int[instance.numAttributes()];
int vals = 0;
for (int i = 0; i < instance.numAttributes(); i++) {
if (instance.value(i) != 0) {
tempValues[vals] = instance.value(i);
tempIndices[vals] = i;
vals++;
}
}
m_AttValues = new double[vals];
m_Indices = new int[vals];
System.arraycopy(tempValues, 0, m_AttValues, 0, vals);
System.arraycopy(tempIndices, 0, m_Indices, 0, vals);
}
}
/**
* Private function to compute default number of accurate instances in the specified data for the
* consequent of the rule
*
* @param data the data in question
* @return the default accuracy number
*/
private double computeDefAccu(Instances data) {
double defAccu = 0;
for (int i = 0; i < data.numInstances(); i++) {
Instance inst = data.instance(i);
if ((int) inst.classValue() == (int) m_Consequent) defAccu += inst.weight();
}
return defAccu;
}
/**
* Processes the given data (may change the provided dataset) and returns the modified version.
* This method is called in batchFinished().
*
* @param instances the data to process
* @return the modified data
* @throws Exception in case the processing goes wrong
* @see #batchFinished()
*/
protected Instances process(Instances instances) throws Exception {
Instances result;
int i;
int n;
double[] values;
String value;
Instance inst;
Instance newInst;
// we need the complete input data!
if (!isFirstBatchDone()) setOutputFormat(determineOutputFormat(getInputFormat()));
result = new Instances(getOutputFormat());
for (i = 0; i < instances.numInstances(); i++) {
inst = instances.instance(i);
values = inst.toDoubleArray();
for (n = 0; n < values.length; n++) {
if (!m_Cols.isInRange(n) || !instances.attribute(n).isNumeric() || inst.isMissing(n))
continue;
// get index of value
if (instances.attribute(n).type() == Attribute.DATE) value = inst.stringValue(n);
else value = Utils.doubleToString(inst.value(n), MAX_DECIMALS);
values[n] = result.attribute(n).indexOfValue(value);
}
// generate new instance
if (inst instanceof SparseInstance) newInst = new SparseInstance(inst.weight(), values);
else newInst = new DenseInstance(inst.weight(), values);
// copy possible string, relational values
newInst.setDataset(getOutputFormat());
copyValues(newInst, false, inst.dataset(), getOutputFormat());
result.add(newInst);
}
return result;
}
/**
* Implements the splitData function. This procedure is to split the data into bags according to
* the nominal attribute value The infoGain for each bag is also calculated.
*
* @param data the data to be split
* @param defAcRt the default accuracy rate for data
* @param cl the class label to be predicted
* @return the array of data after split
*/
public Instances[] splitData(Instances data, double defAcRt, double cl) {
int bag = att.numValues();
Instances[] splitData = new Instances[bag];
for (int x = 0; x < bag; x++) {
splitData[x] = new Instances(data, data.numInstances());
accurate[x] = 0;
coverage[x] = 0;
}
for (int x = 0; x < data.numInstances(); x++) {
Instance inst = data.instance(x);
if (!inst.isMissing(att)) {
int v = (int) inst.value(att);
splitData[v].add(inst);
coverage[v] += inst.weight();
if ((int) inst.classValue() == (int) cl) accurate[v] += inst.weight();
}
}
for (int x = 0; x < bag; x++) {
double t = coverage[x] + 1.0;
double p = accurate[x] + 1.0;
double infoGain =
// Utils.eq(defAcRt, 1.0) ?
// accurate[x]/(double)numConds :
accurate[x] * (Utils.log2(p / t) - Utils.log2(defAcRt));
if (infoGain > maxInfoGain) {
maxInfoGain = infoGain;
cover = coverage[x];
accu = accurate[x];
accuRate = p / t;
value = (double) x;
}
}
return splitData;
}
/**
* Inserts an instance into the hash table
*
* @param inst instance to be inserted
* @param instA to create the hash key from
* @throws Exception if the instance can't be inserted
*/
private void insertIntoTable(Instance inst, double[] instA) throws Exception {
double[] tempClassDist2;
double[] newDist;
DecisionTableHashKey thekey;
if (instA != null) {
thekey = new DecisionTableHashKey(instA);
} else {
thekey = new DecisionTableHashKey(inst, inst.numAttributes(), false);
}
// see if this one is already in the table
tempClassDist2 = (double[]) m_entries.get(thekey);
if (tempClassDist2 == null) {
if (m_classIsNominal) {
newDist = new double[m_theInstances.classAttribute().numValues()];
// Leplace estimation
for (int i = 0; i < m_theInstances.classAttribute().numValues(); i++) {
newDist[i] = 1.0;
}
newDist[(int) inst.classValue()] = inst.weight();
// add to the table
m_entries.put(thekey, newDist);
} else {
newDist = new double[2];
newDist[0] = inst.classValue() * inst.weight();
newDist[1] = inst.weight();
// add to the table
m_entries.put(thekey, newDist);
}
} else {
// update the distribution for this instance
if (m_classIsNominal) {
tempClassDist2[(int) inst.classValue()] += inst.weight();
// update the table
m_entries.put(thekey, tempClassDist2);
} else {
tempClassDist2[0] += (inst.classValue() * inst.weight());
tempClassDist2[1] += inst.weight();
// update the table
m_entries.put(thekey, tempClassDist2);
}
}
}
/**
* Prune all the possible final sequences of the rule using the pruning data. The measure used to
* prune the rule is based on flag given.
*
* @param pruneData the pruning data used to prune the rule
* @param useWhole flag to indicate whether use the error rate of the whole pruning data instead
* of the data covered
*/
public void prune(Instances pruneData, boolean useWhole) {
Instances data = pruneData;
double total = data.sumOfWeights();
if (!Utils.gr(total, 0.0)) return;
/* The default accurate # and rate on pruning data */
double defAccu = computeDefAccu(data);
if (m_Debug)
System.err.println(
"Pruning with " + defAccu + " positive data out of " + total + " instances");
int size = m_Antds.size();
if (size == 0) return; // Default rule before pruning
double[] worthRt = new double[size];
double[] coverage = new double[size];
double[] worthValue = new double[size];
for (int w = 0; w < size; w++) {
worthRt[w] = coverage[w] = worthValue[w] = 0.0;
}
/* Calculate accuracy parameters for all the antecedents in this rule */
double tn = 0.0; // True negative if useWhole
for (int x = 0; x < size; x++) {
Antd antd = (Antd) m_Antds.elementAt(x);
Instances newData = data;
data = new Instances(newData, 0); // Make data empty
for (int y = 0; y < newData.numInstances(); y++) {
Instance ins = newData.instance(y);
if (antd.covers(ins) > 0) { // Covered by this antecedent
coverage[x] += ins.weight();
data.add(ins); // Add to data for further pruning
if ((int) ins.classValue() == (int) m_Consequent) // Accurate prediction
worthValue[x] += ins.weight();
} else if (useWhole) { // Not covered
if ((int) ins.classValue() != (int) m_Consequent) tn += ins.weight();
}
}
if (useWhole) {
worthValue[x] += tn;
worthRt[x] = worthValue[x] / total;
} else // Note if coverage is 0, accuracy is 0.5
worthRt[x] = (worthValue[x] + 1.0) / (coverage[x] + 2.0);
}
double maxValue = (defAccu + 1.0) / (total + 2.0);
int maxIndex = -1;
for (int i = 0; i < worthValue.length; i++) {
if (m_Debug) {
double denom = useWhole ? total : coverage[i];
System.err.println(
i
+ "(useAccuray? "
+ !useWhole
+ "): "
+ worthRt[i]
+ "="
+ worthValue[i]
+ "/"
+ denom);
}
if (worthRt[i] > maxValue) { // Prefer to the
maxValue = worthRt[i]; // shorter rule
maxIndex = i;
}
}
if (maxIndex == -1) return;
/* Prune the antecedents according to the accuracy parameters */
for (int z = size - 1; z > maxIndex; z--) m_Antds.removeElementAt(z);
}
/**
* Calculates the class membership probabilities for the given test instance.
*
* @param instance the instance to be classified
* @return preedicted class probability distribution
* @throws Exception if distribution can't be computed successfully
*/
public double[] distributionForInstance(Instance instance) throws Exception {
// default model?
if (m_ZeroR != null) {
return m_ZeroR.distributionForInstance(instance);
}
if (m_Train.numInstances() == 0) {
throw new Exception("No training instances!");
}
m_NNSearch.addInstanceInfo(instance);
int k = m_Train.numInstances();
if ((!m_UseAllK && (m_kNN < k)) /*&&
!(m_WeightKernel==INVERSE ||
m_WeightKernel==GAUSS)*/) {
k = m_kNN;
}
Instances neighbours = m_NNSearch.kNearestNeighbours(instance, k);
double distances[] = m_NNSearch.getDistances();
if (m_Debug) {
System.out.println("Test Instance: " + instance);
System.out.println(
"For "
+ k
+ " kept "
+ neighbours.numInstances()
+ " out of "
+ m_Train.numInstances()
+ " instances.");
}
// IF LinearNN has skipped so much that <k neighbours are remaining.
if (k > distances.length) k = distances.length;
if (m_Debug) {
System.out.println("Instance Distances");
for (int i = 0; i < distances.length; i++) {
System.out.println("" + distances[i]);
}
}
// Determine the bandwidth
double bandwidth = distances[k - 1];
// Check for bandwidth zero
if (bandwidth <= 0) {
// if the kth distance is zero than give all instances the same weight
for (int i = 0; i < distances.length; i++) distances[i] = 1;
} else {
// Rescale the distances by the bandwidth
for (int i = 0; i < distances.length; i++) distances[i] = distances[i] / bandwidth;
}
// Pass the distances through a weighting kernel
for (int i = 0; i < distances.length; i++) {
switch (m_WeightKernel) {
case LINEAR:
distances[i] = 1.0001 - distances[i];
break;
case EPANECHNIKOV:
distances[i] = 3 / 4D * (1.0001 - distances[i] * distances[i]);
break;
case TRICUBE:
distances[i] = Math.pow((1.0001 - Math.pow(distances[i], 3)), 3);
break;
case CONSTANT:
// System.err.println("using constant kernel");
distances[i] = 1;
break;
case INVERSE:
distances[i] = 1.0 / (1.0 + distances[i]);
break;
case GAUSS:
distances[i] = Math.exp(-distances[i] * distances[i]);
break;
}
}
if (m_Debug) {
System.out.println("Instance Weights");
for (int i = 0; i < distances.length; i++) {
System.out.println("" + distances[i]);
}
}
// Set the weights on the training data
double sumOfWeights = 0, newSumOfWeights = 0;
for (int i = 0; i < distances.length; i++) {
double weight = distances[i];
Instance inst = (Instance) neighbours.instance(i);
sumOfWeights += inst.weight();
newSumOfWeights += inst.weight() * weight;
inst.setWeight(inst.weight() * weight);
// weightedTrain.add(newInst);
}
// Rescale weights
for (int i = 0; i < neighbours.numInstances(); i++) {
Instance inst = neighbours.instance(i);
inst.setWeight(inst.weight() * sumOfWeights / newSumOfWeights);
}
// Create a weighted classifier
m_Classifier.buildClassifier(neighbours);
if (m_Debug) {
System.out.println("Classifying test instance: " + instance);
System.out.println("Built base classifier:\n" + m_Classifier.toString());
}
// Return the classifier's predictions
return m_Classifier.distributionForInstance(instance);
}
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;
}
}
/**
* Calculates the accuracy on a test fold for internal cross validation of feature sets
*
* @param fold set of instances to be "left out" and classified
* @param fs currently selected feature set
* @return the accuracy for the fold
* @throws Exception if something goes wrong
*/
double evaluateFoldCV(Instances fold, int[] fs) throws Exception {
int i;
int ruleCount = 0;
int numFold = fold.numInstances();
int numCl = m_theInstances.classAttribute().numValues();
double[][] class_distribs = new double[numFold][numCl];
double[] instA = new double[fs.length];
double[] normDist;
DecisionTableHashKey thekey;
double acc = 0.0;
int classI = m_theInstances.classIndex();
Instance inst;
if (m_classIsNominal) {
normDist = new double[numCl];
} else {
normDist = new double[2];
}
// first *remove* instances
for (i = 0; i < numFold; i++) {
inst = fold.instance(i);
for (int j = 0; j < fs.length; j++) {
if (fs[j] == classI) {
instA[j] = Double.MAX_VALUE; // missing for the class
} else if (inst.isMissing(fs[j])) {
instA[j] = Double.MAX_VALUE;
} else {
instA[j] = inst.value(fs[j]);
}
}
thekey = new DecisionTableHashKey(instA);
if ((class_distribs[i] = (double[]) m_entries.get(thekey)) == null) {
throw new Error("This should never happen!");
} else {
if (m_classIsNominal) {
class_distribs[i][(int) inst.classValue()] -= inst.weight();
} else {
class_distribs[i][0] -= (inst.classValue() * inst.weight());
class_distribs[i][1] -= inst.weight();
}
ruleCount++;
}
m_classPriorCounts[(int) inst.classValue()] -= inst.weight();
}
double[] classPriors = m_classPriorCounts.clone();
Utils.normalize(classPriors);
// now classify instances
for (i = 0; i < numFold; i++) {
inst = fold.instance(i);
System.arraycopy(class_distribs[i], 0, normDist, 0, normDist.length);
if (m_classIsNominal) {
boolean ok = false;
for (int j = 0; j < normDist.length; j++) {
if (Utils.gr(normDist[j], 1.0)) {
ok = true;
break;
}
}
if (!ok) { // majority class
normDist = classPriors.clone();
}
// if (ok) {
Utils.normalize(normDist);
if (m_evaluationMeasure == EVAL_AUC) {
m_evaluation.evaluateModelOnceAndRecordPrediction(normDist, inst);
} else {
m_evaluation.evaluateModelOnce(normDist, inst);
}
/* } else {
normDist[(int)m_majority] = 1.0;
if (m_evaluationMeasure == EVAL_AUC) {
m_evaluation.evaluateModelOnceAndRecordPrediction(normDist, inst);
} else {
m_evaluation.evaluateModelOnce(normDist, inst);
}
} */
} else {
if (Utils.eq(normDist[1], 0.0)) {
double[] temp = new double[1];
temp[0] = m_majority;
m_evaluation.evaluateModelOnce(temp, inst);
} else {
double[] temp = new double[1];
temp[0] = normDist[0] / normDist[1];
m_evaluation.evaluateModelOnce(temp, inst);
}
}
}
// now re-insert instances
for (i = 0; i < numFold; i++) {
inst = fold.instance(i);
m_classPriorCounts[(int) inst.classValue()] += inst.weight();
if (m_classIsNominal) {
class_distribs[i][(int) inst.classValue()] += inst.weight();
} else {
class_distribs[i][0] += (inst.classValue() * inst.weight());
class_distribs[i][1] += inst.weight();
}
}
return acc;
}
/**
* Classifies an instance for internal leave one out cross validation of feature sets
*
* @param instance instance to be "left out" and classified
* @param instA feature values of the selected features for the instance
* @return the classification of the instance
* @throws Exception if something goes wrong
*/
double evaluateInstanceLeaveOneOut(Instance instance, double[] instA) throws Exception {
DecisionTableHashKey thekey;
double[] tempDist;
double[] normDist;
thekey = new DecisionTableHashKey(instA);
if (m_classIsNominal) {
// if this one is not in the table
if ((tempDist = (double[]) m_entries.get(thekey)) == null) {
throw new Error("This should never happen!");
} else {
normDist = new double[tempDist.length];
System.arraycopy(tempDist, 0, normDist, 0, tempDist.length);
normDist[(int) instance.classValue()] -= instance.weight();
// update the table
// first check to see if the class counts are all zero now
boolean ok = false;
for (int i = 0; i < normDist.length; i++) {
if (Utils.gr(normDist[i], 1.0)) {
ok = true;
break;
}
}
// downdate the class prior counts
m_classPriorCounts[(int) instance.classValue()] -= instance.weight();
double[] classPriors = m_classPriorCounts.clone();
Utils.normalize(classPriors);
if (!ok) { // majority class
normDist = classPriors;
}
m_classPriorCounts[(int) instance.classValue()] += instance.weight();
// if (ok) {
Utils.normalize(normDist);
if (m_evaluationMeasure == EVAL_AUC) {
m_evaluation.evaluateModelOnceAndRecordPrediction(normDist, instance);
} else {
m_evaluation.evaluateModelOnce(normDist, instance);
}
return Utils.maxIndex(normDist);
/*} else {
normDist = new double [normDist.length];
normDist[(int)m_majority] = 1.0;
if (m_evaluationMeasure == EVAL_AUC) {
m_evaluation.evaluateModelOnceAndRecordPrediction(normDist, instance);
} else {
m_evaluation.evaluateModelOnce(normDist, instance);
}
return m_majority;
} */
}
// return Utils.maxIndex(tempDist);
} else {
// see if this one is already in the table
if ((tempDist = (double[]) m_entries.get(thekey)) != null) {
normDist = new double[tempDist.length];
System.arraycopy(tempDist, 0, normDist, 0, tempDist.length);
normDist[0] -= (instance.classValue() * instance.weight());
normDist[1] -= instance.weight();
if (Utils.eq(normDist[1], 0.0)) {
double[] temp = new double[1];
temp[0] = m_majority;
m_evaluation.evaluateModelOnce(temp, instance);
return m_majority;
} else {
double[] temp = new double[1];
temp[0] = normDist[0] / normDist[1];
m_evaluation.evaluateModelOnce(temp, instance);
return temp[0];
}
} else {
throw new Error("This should never happen!");
}
}
// shouldn't get here
// return 0.0;
}
/**
* Generates the classifier.
*
* @param data set of instances serving as training data
* @throws Exception if the classifier has not been generated successfully
*/
public void buildClassifier(Instances data) throws Exception {
// can classifier handle the data?
getCapabilities().testWithFail(data);
// remove instances with missing class
m_theInstances = new Instances(data);
m_theInstances.deleteWithMissingClass();
m_rr = new Random(1);
if (m_theInstances.classAttribute().isNominal()) { // Set up class priors
m_classPriorCounts = new double[data.classAttribute().numValues()];
Arrays.fill(m_classPriorCounts, 1.0);
for (int i = 0; i < data.numInstances(); i++) {
Instance curr = data.instance(i);
m_classPriorCounts[(int) curr.classValue()] += curr.weight();
}
m_classPriors = m_classPriorCounts.clone();
Utils.normalize(m_classPriors);
}
setUpEvaluator();
if (m_theInstances.classAttribute().isNumeric()) {
m_disTransform = new weka.filters.unsupervised.attribute.Discretize();
m_classIsNominal = false;
// use binned discretisation if the class is numeric
((weka.filters.unsupervised.attribute.Discretize) m_disTransform).setBins(10);
((weka.filters.unsupervised.attribute.Discretize) m_disTransform).setInvertSelection(true);
// Discretize all attributes EXCEPT the class
String rangeList = "";
rangeList += (m_theInstances.classIndex() + 1);
// System.out.println("The class col: "+m_theInstances.classIndex());
((weka.filters.unsupervised.attribute.Discretize) m_disTransform)
.setAttributeIndices(rangeList);
} else {
m_disTransform = new weka.filters.supervised.attribute.Discretize();
((weka.filters.supervised.attribute.Discretize) m_disTransform).setUseBetterEncoding(true);
m_classIsNominal = true;
}
m_disTransform.setInputFormat(m_theInstances);
m_theInstances = Filter.useFilter(m_theInstances, m_disTransform);
m_numAttributes = m_theInstances.numAttributes();
m_numInstances = m_theInstances.numInstances();
m_majority = m_theInstances.meanOrMode(m_theInstances.classAttribute());
// Perform the search
int[] selected = m_search.search(m_evaluator, m_theInstances);
m_decisionFeatures = new int[selected.length + 1];
System.arraycopy(selected, 0, m_decisionFeatures, 0, selected.length);
m_decisionFeatures[m_decisionFeatures.length - 1] = m_theInstances.classIndex();
// reduce instances to selected features
m_delTransform = new Remove();
m_delTransform.setInvertSelection(true);
// set features to keep
m_delTransform.setAttributeIndicesArray(m_decisionFeatures);
m_delTransform.setInputFormat(m_theInstances);
m_dtInstances = Filter.useFilter(m_theInstances, m_delTransform);
// reset the number of attributes
m_numAttributes = m_dtInstances.numAttributes();
// create hash table
m_entries = new Hashtable((int) (m_dtInstances.numInstances() * 1.5));
// insert instances into the hash table
for (int i = 0; i < m_numInstances; i++) {
Instance inst = m_dtInstances.instance(i);
insertIntoTable(inst, null);
}
// Replace the global table majority with nearest neighbour?
if (m_useIBk) {
m_ibk = new IBk();
m_ibk.buildClassifier(m_theInstances);
}
// Save memory
if (m_saveMemory) {
m_theInstances = new Instances(m_theInstances, 0);
m_dtInstances = new Instances(m_dtInstances, 0);
}
m_evaluation = null;
}
