private HMMGraph Splitstate(Node qPrime, HMMGraph graph) {
Random random = new Random();
Node q1 = new Node();
foreach (Node x in graph.Nodes) {
q1.SetTransition(x, random.NextDouble());
}
foreach (int symbol in qPrime.Emissions.Keys) {
q1.SetEmission(symbol, qPrime.Emissions[symbol]);
}
q1.InitialProbability = qPrime.InitialProbability;
foreach (Node n in graph.Nodes) {
n.Transitions[q1] = random.NextDouble();
}
q1.SetTransition(q1,random.NextDouble());
graph.AddNode(q1);
graph.Normalize();
return graph;
}
public void RemoveNode(Node n)
{
foreach (Node x in this.Nodes)
{
x.Transitions.Remove(n);
}
Nodes.Remove(n);
}
static HMMGraph CreateGraph(int numberOfSymbols, int numberOfStates, double outDegree)
{
HMMGraph graph = new HMMGraph(numberOfSymbols);
double initialProbabilitySum = 0.0;
for (int i = 0; i < numberOfStates; i++)
{
Node node = new Node();
node.InitialProbability = random.NextDouble();
initialProbabilitySum += node.InitialProbability;
node.Emissions = new Dictionary<int, double>();
for (int j = 0; j < numberOfSymbols; j++)
{
node.Emissions.Add(j, random.NextDouble());
}
double emissionSum = node.Emissions.Values.Sum();
for (int j = 0; j < numberOfSymbols; j++)
{
node.Emissions[j] /= emissionSum;
}
graph.AddNode(node);
}
for (int i = 0; i < numberOfStates; i++)
{
graph.Nodes[i].InitialProbability /= initialProbabilitySum;
graph.Nodes[i].Transitions = new Dictionary<Node, double>();
int outDeg = (int)(((i % 2) == 1) ? Math.Floor(outDegree) : Math.Ceiling(outDegree));
for (int j = 0; j < outDeg; j++)
{
graph.Nodes[i].Transitions.Add(graph.Nodes[((i + j) % numberOfStates)], random.NextDouble());
}
double transitionSum = graph.Nodes[i].Transitions.Values.Sum();
for (int j = 0; j < outDeg; j++)
{
graph.Nodes[i].Transitions[graph.Nodes[((i + j) % numberOfStates)]] /= transitionSum;
}
}
return graph;
}
/// <summary>
/// Sets a transition. If a transition exists for the same node, it is overwritten.
/// If probability is 0, the transition is removed
/// </summary>
/// <param name="node"></param>
/// <param name="prob"></param>
public void SetTransition(Node node, double prob) {
if (prob == 0) {
if (Transitions.ContainsKey(node))
Transitions.Remove(node);
}
else {
if (Transitions.ContainsKey(node))
Transitions[node] = prob;
else
Transitions.Add(node, prob);
}
}
public static HMMGraph HMM2Graph(HiddenMarkovModel hmm){
HMMGraph g = new HMMGraph(hmm.Symbols);
Node[] nodes = new Node[hmm.States];
for (int i = 0; i < hmm.States; i++) {
nodes[i] = new Node();
g.AddNode(nodes[i]);
}
for (int i = 0; i < hmm.States; i++) {
nodes[i].InitialProbability = hmm.Probabilities[i];
for (int j = 0; j < hmm.States; j++)
nodes[i].SetTransition(nodes[j], hmm.Transitions[i, j]);
for (int k = 0; k < hmm.Symbols; k++)
nodes[i].SetEmission(k, hmm.Emissions[i, k]);
}
return g;
}
private double ComputeBackward(Node n, HMMGraph G, int t, int[] O) {
if (backward[t,graph.Nodes.IndexOf(n)] == UNASSIGNED)
{
if (t == O.Length - 1)
{
backward[t, graph.Nodes.IndexOf(n)] = 1.0;
}
else
{
double sum = 0;
foreach (Node ni in G.Nodes)
{
//sum += (n.Transitions.Keys.Contains(ni) ? n.Transitions[ni] : MINIMUM_PROB)
// * (ni.Emissions.Keys.Contains(O[t+1]) ? ni.Emissions[O[t + 1]] : MINIMUM_PROB)
// * ComputeBackward(ni, G, t + 1, O);
double trans = (n.Transitions.Keys.Contains(ni) ? n.Transitions[ni] : MINIMUM_PROB);
double emis = (ni.Emissions.Keys.Contains(O[t + 1]) ? ni.Emissions[O[t + 1]] : MINIMUM_PROB);
double bwd = ComputeBackward(ni, G, t + 1, O);
sum += trans * emis * bwd;
//if (trans == 0.0 || emis == 0.0 || bwd == 0.0) {
// Console.WriteLine("stuff");
//}
}
backward[t, graph.Nodes.IndexOf(n)] = sum;
}
}
return backward[t, graph.Nodes.IndexOf(n)];
}
private double ComputeForward(Node n, HMMGraph G, int t, int[] O) {
if (forward[t,graph.Nodes.IndexOf(n)] == UNASSIGNED)
{
if (t == 0)
{
forward[t,graph.Nodes.IndexOf(n)] = n.InitialProbability
* (n.Emissions.Keys.Contains(O[t]) ? n.Emissions[O[t]] : MINIMUM_PROB);
}
else
{
double sum = 0;
foreach (Node ni in G.Nodes)
{
sum += ComputeForward(ni, G, t - 1, O)
* (ni.Transitions.Keys.Contains(n) ? ni.Transitions[n] : MINIMUM_PROB);
}
forward[t, graph.Nodes.IndexOf(n)] = sum
* (n.Emissions.Keys.Contains(O[t]) ? n.Emissions[O[t]] : MINIMUM_PROB);
}
}
return forward[t, graph.Nodes.IndexOf(n)];
}
// return a relative gamma value (Unscaled)
private double ComputeGamma(Node n, HMMGraph G, int t, int[] O) {
//double result = (ComputeForward(n,G,t,O) * ComputeBackward(n, G, t, O))
// / ComputeLikelihood(G,O);
double fwd = ComputeForward(n, G, t, O);
double bwd = ComputeBackward(n, G, t, O);
double likelihood = ComputeLikelihood(G, O);
double result = (fwd * bwd) / likelihood;
return result;
}
public double ComputeGamma(Node n, HMMGraph G, int[] O) {
double sum = 0;
for(int t=0; t<O.Length; t++) {
sum += ComputeGamma(n, G, t, O);
}
return sum;
}
private double ComputeKsi(Node na, Node nb, HMMGraph G,
int t, int[] O) {
return ComputeForward(na, G, t, O)
* (na.Transitions.Keys.Contains(nb) ? na.Transitions[nb] : MINIMUM_PROB)
* (nb.Emissions.Keys.Contains(O[t+1]) ? nb.Emissions[O[t + 1]] : MINIMUM_PROB)
* ComputeBackward(nb, G, t + 1, O);
}
public HMMGraph ToGraph()
{
HMMGraph graph = new HMMGraph(NumberOfSymbols);
for (int i = 0; i < NumberOfStates; i++)
{
Node node = new Node();
node.InitialProbability = initialDistribution[i];
node.Emissions = emissions[i].ToDictionary(j => j, j => emissionProbabilities[i, j]);
graph.AddNode(node);
}
for (int i = 0; i < NumberOfStates; i++)
{
graph.Nodes[i].Transitions = transitionsOut[i].ToDictionary(j => graph.Nodes[j], j => transitionProbabilities[i, j]);
}
return graph;
}
public void AddNode(Node n) {
Nodes.Add(n);
}
private void AssignEmissions(Node qPrime, Node q1, Node q2) {
double sum = qPrime.Emissions.Values.Sum();
var emissions = (from e in qPrime.Emissions
select e).OrderBy(em => em.Value).ToList();
while (q1.Emissions.Values.Sum() < sum / 2) {
q1.Emissions.Add(emissions[0].Key, emissions[0].Value);
emissions.RemoveAt(0);
}
q2.Emissions = emissions.ToDictionary(kv => kv.Key, kv => kv.Value);
}
private void AssignTransitions(Node qPrime, Node q1, Node q2) {
double sum = qPrime.Transitions.Values.Sum();
var trans = (from tr in qPrime.Transitions
select tr).OrderBy(tra => tra.Value).ToList();
while (q1.Transitions.Values.Sum() < sum / 2) {
q1.Transitions.Add(trans[0].Key, trans[0].Value);
trans.RemoveAt(0);
}
q2.Transitions = trans.ToDictionary(kv => kv.Key, kv => kv.Value);
//q1.SetTransition(q1, 0.1);
//q2.SetTransition(q2, 0.1);
}
// Assign incoming transitions to qPrime between q1 and q2
private void AssignIncomingTransitions(Node qPrime, Node q1, Node q2, HMMGraph graph) {
#region Junk
//Dictionary<Node, double> trans = new Dictionary<Node, double>();
//foreach (Node n in graph.Nodes)
//{
// Dictionary<Node, double> trs = n.Transitions;
// foreach (KeyValuePair<Node, double> kv in trs)
// {
// trans.Add(kv.Key, kv.Value);
// }
//}
////Dictionary<Node,double> rTrans = (from t in trans
//// where t.Key == qPrime
//// select t).ToDictionary(x => x.Key, x => x.Value);
//List<KeyValuePair<Node,double>> rTrans = (from t in trans
// where t.Key == qPrime
// select t).ToList();
//var trans = (from n in graph.Nodes
// select n.Transitions.ToList()).SelectMany(x => x);
//var rTrans = (from kv in trans
// where kv.Key == qPrime
// select kv).ToList<KeyValuePair<Node,double>>();
//foreach (KeyValuePair<Node, double> kv in rTrans) {
// if (rTrans.IndexOf(kv) < rTrans.Count / 2) {
// kv.Key = q1;
// }
// else {
// kv.Key = q2;
// }
//(rTrans.IndexOf(kv) < rTrans.Count / 2) ? (kv.Key = q1) : (kv.Key = q2);
#endregion
int tCount = 0;
foreach (Node n in graph.Nodes) {
if (n.Transitions.ContainsKey(qPrime)) {
tCount++;
}
}
int q1Count = 0;
foreach (Node n in graph.Nodes) {
if (n.Transitions.ContainsKey(qPrime)) {
double prob = n.Transitions[qPrime];
n.SetTransition(qPrime, 0);
if (q1Count < tCount / 2) {
n.SetTransition(q1, prob);
}
else {
n.SetTransition(q2, prob);
}
}
}
}
