private WordGraphConfidences ComputeWordGraphConfidences(WordGraph wordGraph)
{
double normalizationFactor = LogSpace.Zero;
var backwardProbs = new double[wordGraph.Arcs.Count];
for (int i = wordGraph.Arcs.Count - 1; i >= 0; i--)
{
WordGraphArc arc = wordGraph.Arcs[i];
double sum = LogSpace.One;
if (!wordGraph.FinalStates.Contains(arc.NextState))
{
sum = LogSpace.Zero;
foreach (int nextArcIndex in wordGraph.GetNextArcIndices(arc.NextState))
{
WordGraphArc nextArc = wordGraph.Arcs[nextArcIndex];
sum = LogSpace.Add(sum, LogSpace.Multiple(nextArc.Score, backwardProbs[nextArcIndex]));
}
}
backwardProbs[i] = sum;
if (arc.PrevState == WordGraph.InitialState)
{
normalizationFactor = LogSpace.Add(normalizationFactor,
LogSpace.Multiple(arc.Score, backwardProbs[i]));
}
}
var rawWpps = new Dictionary <string, Dictionary <int, double> >();
var forwardProbs = new (double Prob, int Index)[wordGraph.Arcs.Count];
private void ComputePrevScores(int state, out double[] prevScores, out int[] stateBestPrevArcs)
{
if (IsEmpty)
{
prevScores = new double[0];
stateBestPrevArcs = new int[0];
return;
}
prevScores = Enumerable.Repeat(LogSpace.Zero, StateCount).ToArray();
stateBestPrevArcs = new int[StateCount];
if (state == InitialState)
{
prevScores[InitialState] = InitialStateScore;
}
else
{
prevScores[state] = 0;
}
var accessibleStates = new HashSet <int> {
state
};
for (int arcIndex = 0; arcIndex < Arcs.Count; arcIndex++)
{
WordGraphArc arc = Arcs[arcIndex];
if (accessibleStates.Contains(arc.PrevState))
{
double score = LogSpace.Multiple(arc.Score, prevScores[arc.PrevState]);
if (score > prevScores[arc.NextState])
{
prevScores[arc.NextState] = score;
stateBestPrevArcs[arc.NextState] = arcIndex;
}
accessibleStates.Add(arc.NextState);
}
else
{
if (!accessibleStates.Contains(arc.NextState))
{
prevScores[arc.NextState] = LogSpace.Zero;
}
}
}
}
public IEnumerable <double> ComputeRestScores()
{
double[] restScores = Enumerable.Repeat(LogSpace.Zero, StateCount).ToArray();
foreach (int state in _finalStates)
{
restScores[state] = InitialStateScore;
}
for (int i = Arcs.Count - 1; i >= 0; i--)
{
WordGraphArc arc = Arcs[i];
double score = LogSpace.Multiple(arc.Score, restScores[arc.NextState]);
if (score > restScores[arc.PrevState])
{
restScores[arc.PrevState] = score;
}
}
return(restScores);
}