/// <summary>
/// Gets the selective tri-phone for each leaf nodes in the tree.
/// </summary>
/// <param name="nodeToTriphone">The selective tri-phone for first node in decision tree. The key is the leaf node, and the tri-phone pair set is the value.</param>
/// <param name="questions">The related questions.</param>
private static void GetSelectiveTriphone(Dictionary<DecisionTreeNode, TriphoneSet> nodeToTriphone,
IDictionary<string, Question> questions)
{
while (true)
{
// Check whether there are some non-leaf nodes?
IEnumerable<DecisionTreeNode> list = nodeToTriphone.Keys.Where(o => o.NodeType == DecisionTreeNodeType.NonLeaf);
if (list.Count() == 0)
{
// All the data are leaf nodes, just break to return them.
break;
}
// Process the first non-leaf node.
DecisionTreeNode node = list.First();
TriphoneSet parentSet = nodeToTriphone[node];
nodeToTriphone.Remove(node);
Question question = questions[node.QuestionName];
// Check the question of this node.
// Copy from parent.
TriphoneSet leftChildSet = parentSet;
TriphoneSet rightChildSet = new TriphoneSet(parentSet);
switch (question.FeatureName)
{
case LabelFeatureNameSet.CentralPhonemeFeatureName:
// It is central phone question.
// Right child (YES child) will only contains the ones which occur simultaneously in the question set and parent set.
// Left child (NO child) will contains the ones which in parent set but not in question set.
rightChildSet.CentralPhones.IntersectWith(question.ValueSet);
leftChildSet.CentralPhones.ExceptWith(question.ValueSet);
break;
case LabelFeatureNameSet.LeftPhonemeFeatureName:
// Left phone question.
// Right child (YES child) will only contains the ones which occur simultaneously in the question set and parent set.
// Left child (NO child) will contains the ones which in parent set but not in question set.
rightChildSet.LeftPhones.IntersectWith(question.ValueSet);
leftChildSet.LeftPhones.ExceptWith(question.ValueSet);
break;
case LabelFeatureNameSet.RightPhonemeFeatureName:
// Right phone question.
// Right child (YES child) will only contains the ones which occur simultaneously in the question set and parent set.
// Left child (NO child) will contains the ones which in parent set but not in question set.
rightChildSet.RightPhones.IntersectWith(question.ValueSet);
leftChildSet.RightPhones.ExceptWith(question.ValueSet);
break;
default:
// This question have nothing about phone. Just copy the set from parent.
break;
}
// Add the two children.
nodeToTriphone.Add(node.LeftChild, leftChildSet);
nodeToTriphone.Add(node.RightChild, rightChildSet);
}
}
/// <summary>
/// Initializes a new instance of the TriphoneSet class as a copy of the given instance.
/// </summary>
/// <param name="set">The set to copied.</param>
public TriphoneSet(TriphoneSet set)
{
LeftPhones = new HashSet<string>(set.LeftPhones.OrderBy(p => p));
CentralPhones = new HashSet<string>(set.CentralPhones.OrderBy(p => p));
RightPhones = new HashSet<string>(set.RightPhones.OrderBy(p => p));
}
/// <summary>
/// Gets the selective tri-phone for each leaf nodes in the tree.
/// </summary>
/// <param name="tree">The given tree.</param>
/// <param name="questions">The related questions.</param>
/// <param name="phonemes">The whole set of phoneme, which is used to initialize the tri-phone pairs.</param>
/// <returns>The selective tri-phone for each leaf node in decision tree.
/// The key is the leaf node, and the tri-phone pair set is the value.</returns>
private static Dictionary<DecisionTreeNode, TriphoneSet> GetSelectiveTriphone(DecisionTree tree, IDictionary<string, Question> questions, HashSet<string> phonemes)
{
Dictionary<DecisionTreeNode, TriphoneSet> nodeToTriphone = new Dictionary<DecisionTreeNode, TriphoneSet>();
// Firstly, generate a whole tri-phone set.
TriphoneSet set = new TriphoneSet(phonemes);
// Phone-dependent tree should resize the central phone set.
string phone = tree.Phone;
if (!Phoneme.IsAnyPhone(phone))
{
set.CentralPhones.Clear();
set.CentralPhones.Add(phone);
}
// Assign the tri-phone set to the root of the tree.
nodeToTriphone.Add(tree.NodeList[0], set);
GetSelectiveTriphone(nodeToTriphone, questions);
return nodeToTriphone;
}