private static DecisionTreeItem InitializeTreeItem(DataSet dataSet, int levelAvailableCount,
List <int> unusedFeatures, bool useId3, ref int nodeIndex)
{
nodeIndex++;
var currentIndex = nodeIndex;
if (dataSet.ClassCount == 1 || levelAvailableCount == 1 || unusedFeatures.Count == 0)
{
return(new DecisionTreeLeaf(dataSet.GetClassByMaxCount(), currentIndex));
}
levelAvailableCount--;
(var _, var usedFeature) = DecisionTreeItem.GetBestDecisionFromDataSet(dataSet, unusedFeatures, out var split);
if (useId3)
{
unusedFeatures.Remove(usedFeature);
}
if (split is null || split.RightPart.ObjectCount == 0 || split.LeftPart.ObjectCount == 0)
{
return(new DecisionTreeLeaf(dataSet.GetClassByMaxCount(), currentIndex));
}
var leftChild = InitializeTreeItem(split.LeftPart, levelAvailableCount, unusedFeatures, useId3, ref nodeIndex);
var rightChild = InitializeTreeItem(split.RightPart, levelAvailableCount, unusedFeatures, useId3, ref nodeIndex);
return(new DecisionTreeNode(leftChild, rightChild, split.SplitItemIndex, split.SplitValue, currentIndex));
}
internal DecisionTreeNode(DecisionTreeItem leftChild, DecisionTreeItem rightChild, int itemDecisionItemIndex, Double compareValue, int nodeIndex) : base(nodeIndex)
{
_leftChild = leftChild;
_rightChild = rightChild;
_decisionItemIndex = itemDecisionItemIndex;
_compareValue = compareValue;
}
private DecisionTree(DecisionTreeItem head, int nodeCount)
{
_head = head;
NodeCount = nodeCount;
}
