// Smoothing of leafs outputs:
// 0 - no smoothing
// 1 - maximal smoothing
public void SmoothLeafOutputs(double parentOutput, double smoothing)
{
double myOutput = (1 - smoothing) * GetWeightedOutput() + smoothing * parentOutput;
if (IsLeaf)
{
Tree.SetOutput(~NodeIndex, myOutput);
}
else
{
LteNode.SmoothLeafOutputs(myOutput, smoothing);
GtNode.SmoothLeafOutputs(myOutput, smoothing);
}
}
/// <summary>
/// Regularize a regression tree with smoothing paramter alpha.
/// </summary>
protected virtual void SmoothTree(InternalRegressionTree tree, double smoothing)
{
if (smoothing == 0.0)
{
return;
}
//Create recursive structure of the tree starting from root node
var regularizer = new RecursiveRegressionTree(tree, TreeLearner.Partitioning, 0);
//Perform bottom-up computation of weighted interior node output
double rootNodeOutput = regularizer.GetWeightedOutput();
//followed by top-down propagation of parent's output value
regularizer.SmoothLeafOutputs(rootNodeOutput, smoothing);
}
