internal void TrainHMMScaled(List <T[]> trainingData)
{
bool iterating = true;
while (iterating)
{
double[] tempPI = new double[initialStateDistribution.Length];
double[,] tempA = new double[stateTransitionProbabilities.GetLength(0), stateTransitionProbabilities.GetLength(1)];
double[,] tempANum = new double[stateTransitionProbabilities.GetLength(0), stateTransitionProbabilities.GetLength(1)];
//double[,] tempADen = new double[stateTransitionProbabilities.GetLength(0), stateTransitionProbabilities.GetLength(1)];
double[] tempADen = new double[stateTransitionProbabilities.GetLength(0)];
double[,] tempB = new double[symbolDistributionDiscrete.GetLength(0), symbolDistributionDiscrete.GetLength(1)];
double[,] tempBNum = new double[symbolDistributionDiscrete.GetLength(0), symbolDistributionDiscrete.GetLength(1)];
double[,] tempBDen = new double[symbolDistributionDiscrete.GetLength(0), symbolDistributionDiscrete.GetLength(1)];
double[,] alpha;
double[,] beta;
double[] c;
DiscreteHMM <T, U> newHMM;
for (int k = 0; k < trainingData.Count; k++)
{
double[, ,] xi = new double[trainingData[k].Length - 1, states.Length, states.Length];
double[,] gamma = new double[trainingData[k].Length, states.Length];
ForwardAndBackwardVariablesScaled(trainingData[k], out alpha, out beta, out c);
double totalProb = FastObservationSequenceProbability(trainingData[k]);
//Compute xi and gamma
for (int t = 0; t < trainingData[k].Length; t++)
{
for (int i = 0; i < states.Length; i++)
{
if (t < trainingData[k].Length - 1)
{
for (int j = 0; j < states.Length; j++)
{
xi[t, i, j] = (alpha[t, i] * stateTransitionProbabilities[i, j] * SymbolProbability(trainingData[k][t + 1], states[j]) * beta[t + 1, j]);
}
}
gamma[t, i] = (alpha[t, i] * beta[t, i]) / c[t];
}
}
for (int i = 0; i < states.Length; i++)
{
tempPI[i] += gamma[0, i];
for (int j = 0; j < states.Length; j++)
{
double aNum = 0;
for (int t = 0; t < trainingData[k].Length - 1; t++)
{
aNum += xi[t, i, j];
}
tempANum[i, j] += aNum;
}
double aDen = 0;
for (int t = 0; t < trainingData[k].Length - 1; t++)
{
aDen += gamma[t, i];
}
tempADen[i] += aDen;
}
for (int j = 0; j < states.Length; j++)
{
for (int v = 0; v < symbols.Length; v++)
{
double bNum = 0.0;
double bDen = 0.0;
for (int t = 0; t < trainingData[k].Length; t++)
{
if (trainingData[k][t].Equals(symbols[v]))
{
bNum += gamma[t, j];
}
bDen += gamma[t, j];
}
tempBNum[j, v] += bNum;
tempBDen[j, v] += bDen;
}
}
}
//Calculate the final reestimated values
for (int i = 0; i < states.Length; i++)
{
tempPI[i] = tempPI[i] / (double)trainingData.Count; //this isn't in Rabiner's tutorial; however, I think it is needed to reestimate ergodic models from multiple sequences
for (int j = 0; j < states.Length; j++)
{
tempA[i, j] = tempANum[i, j] / tempADen[i];
}
for (int v = 0; v < symbols.Length; v++)
{
tempB[i, v] = tempBNum[i, v] / tempBDen[i, v];
}
}
newHMM = new DiscreteHMM <T, U>(symbols, states, tempA, tempPI, tempB);
double pOld = 0.0;
double pNew = 0.0;
for (int k = 0; k < trainingData.Count; k++)
{
pOld += LogFastObservationSequenceProbability(trainingData[k]); //If you want to multiply variables, you add the logs... DUH!
pNew += newHMM.LogFastObservationSequenceProbability(trainingData[k]);
}
if (pNew > pOld + .00000001) //Add some error margin so this won't loop forever
{
Array.Copy(tempPI, initialStateDistribution, tempPI.Length);
Array.Copy(tempA, stateTransitionProbabilities, tempA.Length);
Array.Copy(tempB, symbolDistributionDiscrete, tempB.Length);
}
else
{
iterating = false;
}
}
}
internal GestureRecognizer(HMMModel model)
{
hmm = new DiscreteHMM <int, int>(model, symbols, states);
}
internal void TrainHMM(T[] trainingData)
{
bool iterating = true;
double[] tempPI = new double[initialStateDistribution.Length];
double[,] tempA = new double[stateTransitionProbabilities.GetLength(0), stateTransitionProbabilities.GetLength(1)];
double[,] tempB = new double[symbolDistributionDiscrete.GetLength(0), symbolDistributionDiscrete.GetLength(1)];
double[,] alpha;
double[,] beta;
double[, ,] xi = new double[trainingData.Length - 1, states.Length, states.Length];
double[,] gamma = new double[trainingData.Length, states.Length];
DiscreteHMM <T, U> newHMM;
while (iterating)
{
alpha = ForwardVariables(trainingData);
beta = BackwardVariables(trainingData);
double totalProb = FastObservationSequenceProbability(trainingData);
//Compute xi and gamma
for (int t = 0; t < trainingData.Length; t++)
{
for (int i = 0; i < states.Length; i++)
{
if (t < trainingData.Length - 1)
{
for (int j = 0; j < states.Length; j++)
{
xi[t, i, j] = (alpha[t, i] * stateTransitionProbabilities[i, j] * SymbolProbability(trainingData[t + 1], states[j]) * beta[t + 1, j]) / totalProb;
}
}
gamma[t, i] = (alpha[t, i] * beta[t, i]) / totalProb;
}
}
for (int i = 0; i < states.Length; i++)
{
tempPI[i] = gamma[0, i];
for (int j = 0; j < states.Length; j++)
{
double aNum = 0;
double aDen = 0;
for (int t = 0; t < trainingData.Length - 1; t++)
{
aNum += xi[t, i, j];
aDen += gamma[t, i];
}
tempA[i, j] = aNum / aDen;
}
}
for (int j = 0; j < states.Length; j++)
{
for (int k = 0; k < symbols.Length; k++)
{
double bNum = 0.0;
double bDen = 0.0;
for (int t = 0; t < trainingData.Length; t++)
{
if (trainingData[t].Equals(symbols[k]))
{
bNum += gamma[t, j];
}
bDen += gamma[t, j];
}
tempB[j, k] = bNum / bDen;
}
}
newHMM = new DiscreteHMM <T, U>(symbols, states, tempA, tempPI, tempB);
if (newHMM.LogFastObservationSequenceProbability(trainingData) > LogFastObservationSequenceProbability(trainingData))
{
Array.Copy(tempPI, initialStateDistribution, tempPI.Length);
Array.Copy(tempA, stateTransitionProbabilities, tempA.Length);
Array.Copy(tempB, symbolDistributionDiscrete, tempB.Length);
}
else
{
iterating = false;
}
}
}
