Ejemplo n.º 1
0
  public boolean train(
      InstanceList ilist, InstanceList validation, InstanceList testing, TransducerEvaluator eval) {
    assert (ilist.size() > 0);
    if (emissionEstimator == null) {
      emissionEstimator = new Multinomial.LaplaceEstimator[numStates()];
      transitionEstimator = new Multinomial.LaplaceEstimator[numStates()];
      emissionMultinomial = new Multinomial[numStates()];
      transitionMultinomial = new Multinomial[numStates()];
      Alphabet transitionAlphabet = new Alphabet();
      for (int i = 0; i < numStates(); i++)
        transitionAlphabet.lookupIndex(((State) states.get(i)).getName(), true);
      for (int i = 0; i < numStates(); i++) {
        emissionEstimator[i] = new Multinomial.LaplaceEstimator(inputAlphabet);
        transitionEstimator[i] = new Multinomial.LaplaceEstimator(transitionAlphabet);
        emissionMultinomial[i] =
            new Multinomial(getUniformArray(inputAlphabet.size()), inputAlphabet);
        transitionMultinomial[i] =
            new Multinomial(getUniformArray(transitionAlphabet.size()), transitionAlphabet);
      }
      initialEstimator = new Multinomial.LaplaceEstimator(transitionAlphabet);
    }
    for (Instance instance : ilist) {
      FeatureSequence input = (FeatureSequence) instance.getData();
      FeatureSequence output = (FeatureSequence) instance.getTarget();
      new SumLatticeDefault(this, input, output, new Incrementor());
    }
    initialMultinomial = initialEstimator.estimate();
    for (int i = 0; i < numStates(); i++) {
      emissionMultinomial[i] = emissionEstimator[i].estimate();
      transitionMultinomial[i] = transitionEstimator[i].estimate();
      getState(i).setInitialWeight(initialMultinomial.logProbability(getState(i).getName()));
    }

    return true;
  }
Ejemplo n.º 2
0
 public void estimate() {
   Alphabet transitionAlphabet = getTransitionAlphabet();
   initialMultinomial = initialEstimator.estimate();
   initialEstimator = new Multinomial.LaplaceEstimator(transitionAlphabet);
   for (int i = 0; i < numStates(); i++) {
     State s = (State) getState(i);
     emissionMultinomial[i] = emissionEstimator[i].estimate();
     transitionMultinomial[i] = transitionEstimator[i].estimate();
     s.setInitialWeight(initialMultinomial.logProbability(s.getName()));
     // reset estimators
     emissionEstimator[i] = new Multinomial.LaplaceEstimator(inputAlphabet);
     transitionEstimator[i] = new Multinomial.LaplaceEstimator(transitionAlphabet);
   }
 }
Ejemplo n.º 3
0
 /**
  * Separate initialization of initial/transitions and emissions. All probabilities are
  * proportional to (1+Uniform[0,1])^noise.
  *
  * @author kedarb
  * @param random Random object (if null use uniform distribution)
  * @param noise Noise exponent to use. If zero, then uniform distribution.
  */
 public void initTransitions(Random random, double noise) {
   Alphabet transitionAlphabet = getTransitionAlphabet();
   initialMultinomial =
       new Multinomial(
           getRandomArray(transitionAlphabet.size(), random, noise), transitionAlphabet);
   initialEstimator = new Multinomial.LaplaceEstimator(transitionAlphabet);
   transitionMultinomial = new Multinomial[numStates()];
   transitionEstimator = new Multinomial.LaplaceEstimator[numStates()];
   for (int i = 0; i < numStates(); i++) {
     transitionMultinomial[i] =
         new Multinomial(
             getRandomArray(transitionAlphabet.size(), random, noise), transitionAlphabet);
     transitionEstimator[i] = new Multinomial.LaplaceEstimator(transitionAlphabet);
     // set state's initial weight
     State s = (State) getState(i);
     s.setInitialWeight(initialMultinomial.logProbability(s.getName()));
   }
 }