double P()
{
if (fb == null || fb.Count == 0)
{
throw new Exception("You have to call DoWork() first");
}
return(StateSpace.Sum(state => fb[state][T - 1]));
}
public override double P()
{
if (fb == null || fb.Count == 0)
{
throw new Exception("You have to call DoWork() first");
}
return
(StateSpace.Sum(
state =>
InitialProbabilitiesOfStates[state] * EmissionMatrix[state, SequenceOfObservations[0]] *
fb[state][0]));
}
private void ValidateParameters()
{
if (EmissionMatrix == null || TransitionMatrix == null || SequenceOfObservations == null ||
StateSpace == null || ObservationSpace == null)
{
throw new ArgumentException("Parameters cannot be null");
}
if (ObservationSpace.Length != EmissionMatrix.GetLength(1) || ObservationSpace.Length == 0)
{
throw new ArgumentException("N should be greater than 0 and consistent");
}
#if _USE_ARRAYS_INSTEAD_OF_MATRIX_HASHTABLE
if (StateSpace.Length != TransitionMatrix.GetLength(0) || TransitionMatrix.GetLength(0) != TransitionMatrix.GetLength(1) || TransitionMatrix.GetLength(1) != EmissionMatrix.GetLength(0) || EmissionMatrix.GetLength(0) != InitialProbabilitiesOfStates.Length || StateSpace.Length == 0)
{
throw new ArgumentException("K should be greater than 0 and consistent");
}
#else
if (StateSpace.Length != TransitionMatrix.GetLength(0) ||
TransitionMatrix.GetLength(0) != TransitionMatrix.GetLength(1) ||
TransitionMatrix.GetLength(1) != EmissionMatrix.GetLength(0) ||
EmissionMatrix.GetLength(0) != InitialProbabilitiesOfStates.Count || StateSpace.Length == 0)
{
throw new ArgumentException("K should be greater than 0 and consistent");
}
#endif
if (SequenceOfObservations.Length == 0)
{
throw new ArgumentException("T should be greater than 0 and consistent");
}
if (
StateSpace.Select(state => ObservationSpace.Sum(observation => EmissionMatrix[state, observation]))
.Any(sum => sum <= 0.99 || sum >= 1.01))
{
throw new ArgumentException("EmissionMatrix has not normalized probabilities"); //Exception("Emi");
}
if (
StateSpace.Select(state1 => StateSpace.Sum(state2 => TransitionMatrix[state1, state2]))
.Any(sum => sum <= 0.99 || sum >= 1.01))
{
throw new ArgumentException("TransitionMatrix has not normalized probabilities"); //Exception("Emi");
}
}
public override void DoWork()
{
base.DoWork();
AlphaPass();
BetaPass();
_probabilitySuffix = StateSpace.Sum(
state =>
InitialProbabilitiesOfStates[state] * EmissionMatrix[state, SequenceOfObservations[0]] *
beta[state][0]);
_probabilityPrefix = StateSpace.Sum(state => alpha[state][T - 1]);
var TOLERANCE = 1e-3;
if (Math.Abs((_probabilitySuffix - _probabilityPrefix) / _probabilityPrefix) > TOLERANCE)
{
throw new Exception("Probabilities are not equal");
}
// Probability = (_probabilitySuffix + _probabilityPrefix)/2.0;
LogProbability = 0.0;
for (int i = 0; i < T; i++)
{
LogProbability -= Math.Log(c[i]);
}
Probability = Math.Exp(LogProbability);
Output = new TState[T];
for (var i = 0; i < T; i++)
{
var mostProbableState = StateSpace.Aggregate(
(s1, s2) =>
alpha[s1][i] * beta[s1][i] >
alpha[s2][i] * beta[s2][i]
? s1
: s2);
Output[i] = mostProbableState;
}
}
public override void DoWork()
{
base.DoWork();
foreach (var state in StateSpace)
{
fb[state][T - 1] = 1;
//InitialProbabilitiesOfStates[state] * EmissionMatrix[state, SequenceOfObservations[T - 1]];
}
for (var i = T - 2; i >= 0; i--)
{
foreach (var kState in StateSpace)
{
fb[kState][i] =
StateSpace.Sum(
lState =>
TransitionMatrix[kState, lState] * EmissionMatrix[lState, SequenceOfObservations[i + 1]] *
fb[lState][i + 1]);
}
}
}