public static DecisionTree BuildFromDataSet(DataSetObject[] dataSet, int maxHeight)
{
var headNodeDecision = DecisionTreeItem.GetBestDecisionFromDataSet(dataSet, out NodeSplit split);
var headNode = InitializeTreeItem(headNodeDecision, dataSet, split, maxHeight);
return(new DecisionTree(headNode));
}
private static DecisionTreeItem InitializeTreeItem(Decision decision, IReadOnlyCollection <DataSetObject> dataSet, NodeSplit curSplit, int levelAvailableCount)
{
var label = dataSet.First().Label;
if (dataSet.All(k => k.Label == label))
{
return(new DecisionTreeLeaf(dataSet.First().Label));
}
if (levelAvailableCount == 1)
{
return(new DecisionTreeLeaf(dataSet.GetClassByMaxCount()));
}
levelAvailableCount--;
var leftDecision = DecisionTreeItem.GetBestDecisionFromDataSet(curSplit.LeftPart, out var leftSplit);
var leftChild = InitializeTreeItem(leftDecision, curSplit.LeftPart, leftSplit, levelAvailableCount);
var rightDecision = DecisionTreeItem.GetBestDecisionFromDataSet(curSplit.RightPart, out var rightSplit);
var rightChild = InitializeTreeItem(rightDecision, curSplit.RightPart, rightSplit, levelAvailableCount);
return(new DecisionTreeNode(leftChild, rightChild, decision, dataSet.GetClassByMaxCount()));
}
internal DecisionTreeNode(DecisionTreeItem leftChild, DecisionTreeItem rightChild, Decision decision, int decisionResult) : base(decisionResult)
{
_leftChild = leftChild;
_rightChild = rightChild;
_decision = decision;
}
private DecisionTree(DecisionTreeItem head)
{
_head = head;
}