crf.java

这是一个matlab的java实现。里面有许多内容。请大家慢慢捉摸。

																						TransducerEvaluator eval, int numIterations,
																						int numIterationsBetweenFeatureInductions,
																						int numFeatureInductions,
																						int numFeaturesPerFeatureInduction,
																						double trueLabelProbThreshold,
																						boolean clusteredFeatureInduction,
																						double[] trainingProportions)
	{
		int trainingIteration = 0;
		int numLabels = outputAlphabet.size();
		
		for (int featureInductionIteration = 0;
				 featureInductionIteration < numFeatureInductions;
				 featureInductionIteration++)
		{
			// Print out some feature information
			logger.info ("Feature induction iteration "+featureInductionIteration);

			// Train the CRF
			InstanceList theTrainingData = trainingData;
			if (trainingProportions != null && featureInductionIteration < trainingProportions.length) {
				logger.info ("Training on "+trainingProportions[featureInductionIteration]+"% of the data this round.");
				InstanceList[] sampledTrainingData = trainingData.split (new Random(1),
																																	new double[] {trainingProportions[featureInductionIteration],
																																								1-trainingProportions[featureInductionIteration]});
				theTrainingData = sampledTrainingData[0];
			}
			boolean converged = this.train (theTrainingData, validationData, testingData,
																			eval, numIterationsBetweenFeatureInductions);
			trainingIteration += numIterationsBetweenFeatureInductions;

			logger.info ("Starting feature induction with "+inputAlphabet.size()+" features.");
			
			// Create the list of error tokens, for both unclustered and clustered feature induction
			InstanceList errorInstances = new InstanceList (trainingData.getDataAlphabet(),
																												trainingData.getTargetAlphabet());
			ArrayList errorLabelVectors = new ArrayList();
			InstanceList clusteredErrorInstances[][] = new InstanceList[numLabels][numLabels];
			ArrayList clusteredErrorLabelVectors[][] = new ArrayList[numLabels][numLabels];
			
			for (int i = 0; i < numLabels; i++)
				for (int j = 0; j < numLabels; j++) {
					clusteredErrorInstances[i][j] = new InstanceList (trainingData.getDataAlphabet(),
																														 trainingData.getTargetAlphabet());
					clusteredErrorLabelVectors[i][j] = new ArrayList();
				}
			
			for (int i = 0; i < theTrainingData.size(); i++) {
				logger.info ("instance="+i);
				Instance instance = theTrainingData.getInstance(i);
				Sequence input = (Sequence) instance.getData();
				Sequence trueOutput = (Sequence) instance.getTarget();
				assert (input.size() == trueOutput.size());
				Transducer.Lattice lattice = this.forwardBackward (input, null, false,
																													 (LabelAlphabet)theTrainingData.getTargetAlphabet());
				int prevLabelIndex = 0;					// This will put extra error instances in this cluster
				for (int j = 0; j < trueOutput.size(); j++) {
					Label label = (Label) ((LabelSequence)trueOutput).getLabelAtPosition(j);
					assert (label != null);
					//System.out.println ("Instance="+i+" position="+j+" fv="+lattice.getLabelingAtPosition(j).toString(true));
					LabelVector latticeLabeling = lattice.getLabelingAtPosition(j);
					double trueLabelProb = latticeLabeling.value(label.getIndex());
					int labelIndex = latticeLabeling.getBestIndex();
					//System.out.println ("position="+j+" trueLabelProb="+trueLabelProb);
					if (trueLabelProb < trueLabelProbThreshold) {
						logger.info ("Adding error: instance="+i+" position="+j+" prtrue="+trueLabelProb+
																(label == latticeLabeling.getBestLabel() ? "  " : " *")+
																" truelabel="+label+
																" predlabel="+latticeLabeling.getBestLabel()+
																" fv="+((FeatureVector)input.get(j)).toString(true));
						errorInstances.add (input.get(j), label, null, null);
						errorLabelVectors.add (latticeLabeling);
						clusteredErrorInstances[prevLabelIndex][labelIndex].add (input.get(j), label, null, null);
						clusteredErrorLabelVectors[prevLabelIndex][labelIndex].add (latticeLabeling);
					}
					prevLabelIndex = labelIndex;
				}
			}
			logger.info ("Error instance list size = "+errorInstances.size());
			if (clusteredFeatureInduction) {
				FeatureInducer[][] klfi = new FeatureInducer[numLabels][numLabels];
				for (int i = 0; i < numLabels; i++) {
					for (int j = 0; j < numLabels; j++) {
						logger.info ("Doing feature induction for "+
																outputAlphabet.lookupObject(i)+" -> "+outputAlphabet.lookupObject(j));
						if (clusteredErrorInstances[i][j].size() < 20) {
							logger.info ("..skipping because only "+clusteredErrorInstances[i][j].size()+" instances.");
							continue;
						}
						int s = clusteredErrorLabelVectors[i][j].size();
						LabelVector[] lvs = new LabelVector[s];
						for (int k = 0; k < s; k++)
							lvs[k] = (LabelVector) clusteredErrorLabelVectors[i][j].get(k);
						klfi[i][j] = new FeatureInducer (new ExpGain.Factory (lvs),
																						 clusteredErrorInstances[i][j], 
																						 numFeaturesPerFeatureInduction);
					}
				}
				for (int i = 0; i < numLabels; i++) {
					for (int j = 0; j < numLabels; j++) {
						logger.info ("Adding new induced features for "+
																outputAlphabet.lookupObject(i)+" -> "+outputAlphabet.lookupObject(j));
						if (klfi[i][j] == null) {
							logger.info ("...skipping because no features induced.");
							continue;
						}
						klfi[i][j].induceFeaturesFor (trainingData, false, false);
						klfi[i][j].induceFeaturesFor (testingData, false, false);
					}
				}
				klfi = null;
			} else if (true) {
				int s = errorLabelVectors.size();
				LabelVector[] lvs = new LabelVector[s];
				for (int i = 0; i < s; i++)
					lvs[i] = (LabelVector) errorLabelVectors.get(i);
				FeatureInducer klfi = new FeatureInducer (new ExpGain.Factory (lvs),
																									errorInstances, numFeaturesPerFeatureInduction);
				klfi.induceFeaturesFor (trainingData, false, false);
				klfi.induceFeaturesFor (testingData, false, false);
				klfi = null;
			} else {
				// Currently not ever used
				FeatureInducer igfi = new FeatureInducer (new InfoGain.Factory(), errorInstances,
																									numFeaturesPerFeatureInduction);
				igfi.induceFeaturesFor (trainingData, false, false);
				igfi.induceFeaturesFor (testingData, false, false);
				igfi = null;
			}
			this.growWeightsDimensionToInputAlphabet ();
		}
		return this.train (trainingData, validationData, testingData,
											 eval, numIterations - trainingIteration);
	}
	
	public void write (File f) {
		try {
			ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(f));
			oos.writeObject(this);
			oos.close();
		}
		catch (IOException e) {
			System.err.println("Exception writing file " + f + ": " + e);
		}
	}

	public MinimizableCRF getMinimizableCRF (InstanceList ilist)
	{
		return new MinimizableCRF (ilist, this);
	}




	// Serialization
	// For CRF class

	private static final long serialVersionUID = 1;
	private static final int CURRENT_SERIAL_VERSION = 0;
	static final int NULL_INTEGER = -1;

	/* Need to check for null pointers. */
	private void writeObject (ObjectOutputStream out) throws IOException {
		int i, size;
		out.writeInt (CURRENT_SERIAL_VERSION);
		out.writeObject (inputAlphabet);
		out.writeObject (outputAlphabet);
		size = states.size();
		out.writeInt(size);
		for (i = 0; i<size; i++) {
			out.writeObject(states.get(i));
		}
		size = initialStates.size();
		out.writeInt(size);
		for (i = 0; i <size; i++) {
			out.writeObject(initialStates.get(i));
		}
		out.writeObject(name2state);
		if(weights != null) {
			size = weights.length;
			out.writeInt(size);
			for (i=0; i<size; i++) {
				out.writeObject(weights[i]);
			}
		}
		else {
			out.writeInt(NULL_INTEGER);
		}
		if(constraints != null) {
			size = constraints.length;
			out.writeInt(size);
			for (i=0; i<size; i++) {
				out.writeObject(constraints[i]);
			}
		}
		else {
			out.writeInt(NULL_INTEGER);
		}
		if (expectations != null) {
			size = expectations.length;
			out.writeInt(size);
			for (i=0; i<size; i++) {
				out.writeObject(expectations[i]);
			}
		}
		else {
			out.writeInt(NULL_INTEGER);
		}
		out.writeObject(weightAlphabet);
		out.writeBoolean(trainable);
		out.writeBoolean(gatheringConstraints);
		out.writeInt(defaultFeatureIndex);
		out.writeBoolean(usingHyperbolicPrior);
		out.writeDouble(gaussianPriorVariance);
		out.writeDouble(hyperbolicPriorSlope);
		out.writeDouble(hyperbolicPriorSharpness);
		out.writeBoolean(cachedCostStale);
		out.writeBoolean(cachedGradientStale);
	}
	
	private void readObject (ObjectInputStream in) throws IOException, ClassNotFoundException {
		int size, i;
		int version = in.readInt ();
		inputAlphabet = (Alphabet) in.readObject();
		outputAlphabet = (Alphabet) in.readObject();
		size = in.readInt();
		states = new ArrayList(size);
		for (i=0; i<size; i++) {
			State s = (CRF.State) in.readObject();
			states.add(s);
		}
		size = in.readInt();
		initialStates = new ArrayList();
		for (i=0; i<size; i++) {
			State s = (CRF.State) in.readObject();
			initialStates.add(s);
		}
		name2state = (HashMap) in.readObject();
		size = in.readInt();
		if (size == NULL_INTEGER) {
			weights = null;
		}
		else {
			weights = new DenseVector[size];
			for(i=0; i< size; i++) {
				weights[i] = (DenseVector) in.readObject();
			}
		}
		size = in.readInt();
		if (size == NULL_INTEGER) {
			constraints = null;
		}
		else {
			constraints = new DenseVector[size];
			for(i=0; i< size; i++) {
				constraints[i] = (DenseVector) in.readObject();
			}
		}
		size = in.readInt();
		if (size == NULL_INTEGER) {
			expectations = null;
		}
		else {
			expectations = new DenseVector[size];
			for(i=0; i< size; i++) {
				expectations[i] = (DenseVector)in.readObject();
			}
		}
		weightAlphabet = (Alphabet) in.readObject();
		trainable = in.readBoolean();
		gatheringConstraints = in.readBoolean();
		defaultFeatureIndex = in.readInt();
		usingHyperbolicPrior = in.readBoolean();
		gaussianPriorVariance = in.readDouble();
		hyperbolicPriorSlope = in.readDouble();
		hyperbolicPriorSharpness = in.readDouble();
		cachedCostStale = in.readBoolean();
		cachedGradientStale = in.readBoolean();
	}

	public class MinimizableCRF implements Minimizable.ByGradient, Serializable
	{
		InstanceList trainingSet;
		double cachedCost = -123456789;
		DenseVector cachedGradient;
		BitSet infiniteCosts = null;
		int numParameters;
		CRF crf;

		protected MinimizableCRF (InstanceList ilist, CRF crf)
		{
			// Set up
			this.numParameters = 2 * numStates() + weights.length * (defaultFeatureIndex+1);
			this.trainingSet = ilist;
			this.crf = crf;
			cachedGradient = (DenseVector) getNewMatrix ();

			// This resets and values that may have been in expecations and constraints
			setTrainable (true);

			// Set the contraints by running forward-backward with the *output
			// label sequence provided*, thus restricting it to only those
			// paths that agree with the label sequence.
			gatheringConstraints = true;
			for (int i = 0; i < ilist.size(); i++) {
				Instance instance = ilist.getInstance(i);
				FeatureVectorSequence input = (FeatureVectorSequence) instance.getData();
				FeatureSequence output = (FeatureSequence) instance.getTarget();
				//System.out.println ("Confidence-gathering forward-backward on instance "+i+" of "+ilist.size());
				this.crf.forwardBackward (input, output, true);
			}
			gatheringConstraints = false;
		}

		public Matrix getNewMatrix () { return new DenseVector (numParameters); }

		// Negate initialCost and finalCost because the parameters are in
		// terms of "weights", not "costs".
		
		public Matrix getParameters (Matrix m)
		{
			assert (m instanceof DenseVector && ((Vector)m).singleSize() == numParameters);
			DenseVector parameters = (DenseVector)m;
			int pi = 0;
			for (int i = 0; i < numStates(); i++) {
				State s = (State) getState (i);
				parameters.setValue (pi++, -s.initialCost);
				parameters.setValue (pi++, -s.finalCost);
			}
			for (int i = 0; i < weights.length; i++)