public void AddChild(Value value, Node node)
{
if (children.ContainsKey (value.AsString ())) {
this.children [value.AsString ()] = node;
} else {
this.children.Add (value.AsString (), node);
}
}
private Node DecisionTreeLearner(List<Data> examples, List<Attribute> attributes, List<Data> parent_examples, bool prune=false)
{
if (examples.Count == 0) {
return new Leaf (this.Plurality (parent_examples));
} else if (this.SameClassification (examples)) {
return new Leaf (examples [0].Target);
} else if (attributes.Count == 0) {
return new Leaf (this.Plurality (examples));
} else {
var mostImportantAttribute = this.Importance (examples, attributes);
var filtered_attributes = attributes.ToList ();
filtered_attributes.RemoveAll (x => x.Name == mostImportantAttribute.Name);
var tree = new Node (mostImportantAttribute);
var partitions = this.Partition (examples, mostImportantAttribute);
var values = mostImportantAttribute.Values;
foreach (var kvp in partitions) {
tree.AddChild (kvp.Key, this.DecisionTreeLearner (kvp.Value, filtered_attributes, examples, prune));
if (values.Contains (kvp.Key)) {
values.Remove (kvp.Key);
}
}
foreach (var value in values) {
tree.AddChild (value, new Leaf (this.Plurality (examples)));
}
if (prune && tree.IsEndNode () && !this.IsSignificant (partitions, examples)) {
tree = new Leaf (this.Plurality (examples));
}
return tree;
}
}
