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Trellis

2,013 bytes added, 06:48, 30 April 2010
Created page with ' /** * Builds a Trellis over a sentence, by starting at the state State, and * advancing through all legal extensions of each state already in the …'
/**
* 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);
boolean skipper = false;
if (tagScores.totalCount() != 0) skipper = true;
for (String tag : tagScores.keySet()) {
double score = tagScores.getCount(tag);
if (skipper && Math.abs(score) < 1) continue;
State nextState = state.getNextState(tag);
trellis.setTransitionCount(state, nextState, score);
nextStates.add(nextState);
}
}
// System.out.println("States: "+nextStates);
states = nextStates;
}
//System.out.println("trellis size: bt = " + trellis.btsize() + "; ft = " + trellis.ftsize());
return trellis;
}
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