/**
* 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;
}
public List<S> getBestPath(Trellis<S> trellis) {
List<S> states = new ArrayList<S>();
S currentState = trellis.getStartState();
states.add(currentState);
while (!currentState.equals(trellis.getEndState())) {
Counter<S> transitions = trellis.getForwardTransitions(currentState);
S nextState = transitions.argMax();
states.add(nextState);
currentState = nextState;
}
return states;
}
