Java tutorial
/* * This file is part of the "STARDUST" project. * * (c) Fabian Keller <hello@fabian-keller.de> * * For the full copyright and license information, please view the LICENSE * file that was distributed with this source code. */ package se.de.hu_berlin.informatik.stardust.localizer.machinelearn; import java.util.ArrayList; import java.util.Arrays; import java.util.HashMap; import java.util.List; import java.util.Map; import weka.classifiers.AbstractClassifier; import weka.classifiers.Classifier; import weka.core.Attribute; import weka.core.DenseInstance; import weka.core.Instance; import weka.core.Instances; import se.de.hu_berlin.informatik.stardust.localizer.IFaultLocalizer; import se.de.hu_berlin.informatik.stardust.localizer.SBFLRanking; import se.de.hu_berlin.informatik.stardust.spectra.INode; import se.de.hu_berlin.informatik.stardust.spectra.ISpectra; import se.de.hu_berlin.informatik.stardust.spectra.ITrace; import se.de.hu_berlin.informatik.utils.miscellaneous.Log; /** * Machine learning based fault localization approach using Weka as ML backend. * * ML algorithms can be configured. * * @param <T> * type used to identify nodes in the system */ public class WekaFaultLocalizer<T> implements IFaultLocalizer<T> { /** classifier name */ private final String classifierName; /** options for the classifier */ private final String[] classifierOptions; /** * Construct Weka fault localizer * * @param classifierName * name of the Weka classifier to use */ public WekaFaultLocalizer(final String classifierName) { this(classifierName, new String[0]); } /** * Construct Weka fault localizer * * @param classifierName * name of the Weka classifier to use * @param options * options to pass to the classifier */ public WekaFaultLocalizer(final String classifierName, final String[] options) { super(); this.classifierName = classifierName; if (options == null) { this.classifierOptions = new String[0]; } else { this.classifierOptions = Arrays.copyOf(options, options.length); } } /** * Returns the name of the used classifier * * @return classifier name */ public String getClassifierName() { return this.classifierName; } @Override public SBFLRanking<T> localize(final ISpectra<T> spectra) { // == 1. Create Weka training instance final List<INode<T>> nodes = new ArrayList<>(spectra.getNodes()); // nominal true/false values final List<String> tf = new ArrayList<String>(); tf.add("t"); tf.add("f"); // create an attribute for each component final Map<INode<T>, Attribute> attributeMap = new HashMap<INode<T>, Attribute>(); final ArrayList<Attribute> attributeList = new ArrayList<Attribute>(); // NOCS: Weka needs ArrayList.. for (final INode<T> node : nodes) { final Attribute attribute = new Attribute(node.toString(), tf); attributeList.add(attribute); attributeMap.put(node, attribute); } // create class attribute (trace success) final Attribute successAttribute = new Attribute("success", tf); attributeList.add(successAttribute); // create weka training instance final Instances trainingSet = new Instances("TraceInfoInstances", attributeList, 1); trainingSet.setClassIndex(attributeList.size() - 1); // == 2. add traces to training set // add an instance for each trace for (final ITrace<T> trace : spectra.getTraces()) { final Instance instance = new DenseInstance(nodes.size() + 1); instance.setDataset(trainingSet); for (final INode<T> node : nodes) { instance.setValue(attributeMap.get(node), trace.isInvolved(node) ? "t" : "f"); } instance.setValue(successAttribute, trace.isSuccessful() ? "t" : "f"); trainingSet.add(instance); } // == 3. use prediction to localize faults // build classifier try { final Classifier classifier = this.buildClassifier(this.classifierName, this.classifierOptions, trainingSet); final SBFLRanking<T> ranking = new SBFLRanking<>(); Log.out(this, "begin classifying"); int classified = 0; final Instance instance = new DenseInstance(nodes.size() + 1); instance.setDataset(trainingSet); for (final INode<T> node : nodes) { instance.setValue(attributeMap.get(node), "f"); } instance.setValue(successAttribute, "f"); for (final INode<T> node : nodes) { classified++; if (classified % 1000 == 0) { Log.out(this, String.format("Classified %d nodes.", classified)); } // contain only the current node in the network instance.setValue(attributeMap.get(node), "t"); // predict with which probability this setup leads to a failing network final double[] distribution = classifier.distributionForInstance(instance); ranking.add(node, distribution[1]); // reset involvment for node instance.setValue(attributeMap.get(node), "f"); } return ranking; } catch (final Exception e) { // NOCS: Weka throws only raw exceptions throw new RuntimeException(e); } } /** * Builds and trains a classifier. * * @param name * FQCN of the classifier * @param options * options to pass to the classifier * @param trainingSet * training set to build the classifier with * @return trained classifier */ public Classifier buildClassifier(final String name, final String[] options, final Instances trainingSet) { try { final Classifier classifier = AbstractClassifier.forName(this.classifierName, options); classifier.buildClassifier(trainingSet); return classifier; } catch (final Exception e1) { // NOCS: Weka throws only raw exceptions Log.err(this, "Unable to create classifier " + this.classifierName); throw new RuntimeException(e1); } } @Override public String getName() { assert !this.classifierName.endsWith("."); return "weka-" + this.classifierName.substring(this.classifierName.lastIndexOf(".") + 1); } }