Exemplo n.º 1
0
 /**
  * Builds a Trellis over a sentence, by starting at the state State, and advancing through all
  * legal extensions of each state already in the trellis. You should not have to modify this
  * code (or even read it, really).
  */
 private Trellis<State> buildTrellis(List<String> sentence) {
   Trellis<State> trellis = new Trellis<State>();
   trellis.setStartState(State.getStartState());
   State stopState = State.getStopState(sentence.size() + 2);
   trellis.setStopState(stopState);
   Set<State> states = Collections.singleton(State.getStartState());
   for (int position = 0; position <= sentence.size() + 1; position++) {
     Set<State> nextStates = new HashSet<State>();
     for (State state : states) {
       if (state.equals(stopState)) continue;
       LocalTrigramContext localTrigramContext =
           new LocalTrigramContext(
               sentence, position, state.getPreviousPreviousTag(), state.getPreviousTag());
       Counter<String> tagScores = localTrigramScorer.getLogScoreCounter(localTrigramContext);
       for (String tag : tagScores.keySet()) {
         double score = tagScores.getCount(tag);
         State nextState = state.getNextState(tag);
         trellis.setTransitionCount(state, nextState, score);
         nextStates.add(nextState);
       }
     }
     //        System.out.println("States: "+nextStates);
     states = nextStates;
   }
   return trellis;
 }
Exemplo n.º 2
0
 /**
  * Scores a tagging for a sentence. Note that a tag sequence not accepted by the markov process
  * should receive a log score of Double.NEGATIVE_INFINITY.
  */
 public double scoreTagging(TaggedSentence taggedSentence) {
   double logScore = 0.0;
   List<LabeledLocalTrigramContext> labeledLocalTrigramContexts =
       extractLabeledLocalTrigramContexts(taggedSentence);
   for (LabeledLocalTrigramContext labeledLocalTrigramContext : labeledLocalTrigramContexts) {
     Counter<String> logScoreCounter =
         localTrigramScorer.getLogScoreCounter(labeledLocalTrigramContext);
     String currentTag = labeledLocalTrigramContext.getCurrentTag();
     if (logScoreCounter.containsKey(currentTag)) {
       logScore += logScoreCounter.getCount(currentTag);
     } else {
       logScore += Double.NEGATIVE_INFINITY;
     }
   }
   return logScore;
 }
Exemplo n.º 3
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 // chop up the validation instances into local contexts and pass them on to the local scorer.
 public void validate(List<TaggedSentence> taggedSentences) {
   localTrigramScorer.validate(extractLabeledLocalTrigramContexts(taggedSentences));
 }
Exemplo n.º 4
0
 // chop up the training instances into local contexts and pass them on to the local scorer.
 public void train(List<TaggedSentence> taggedSentences) {
   localTrigramScorer.train(extractLabeledLocalTrigramContexts(taggedSentences));
 }