Developer API

org.apache.spark.mllib.tree.loss

Interface Loss

All Superinterfaces:

java.io.Serializable

public interface Loss
extends scala.Serializable

Trait for adding "pluggable" loss functions for the gradient boosting algorithm.

Method Summary

Modifier and Type	Method and Description
double	computeError(double prediction, double label) Method to calculate loss when the predictions are already known.
double	computeError(org.apache.spark.mllib.tree.model.TreeEnsembleModel model, RDD<LabeledPoint> data) Method to calculate error of the base learner for the gradient boosting calculation.
double	gradient(double prediction, double label) Method to calculate the gradients for the gradient boosting calculation.

Method Detail

computeError

double computeError(org.apache.spark.mllib.tree.model.TreeEnsembleModel model,
                    RDD<LabeledPoint> data)

Method to calculate error of the base learner for the gradient boosting calculation.

Parameters:

model - Model of the weak learner.

data - Training dataset: RDD of LabeledPoint.

Returns:

Measure of model error on data

Note:

This method is not used by the gradient boosting algorithm but is useful for debugging purposes.

computeError

double computeError(double prediction,
                    double label)

Method to calculate loss when the predictions are already known.

Parameters:

prediction - Predicted label.

label - True label.

Returns:

Measure of model error on datapoint.

Note:

This method is used in the method evaluateEachIteration to avoid recomputing the predicted values from previously fit trees.

gradient

double gradient(double prediction,
                double label)

Method to calculate the gradients for the gradient boosting calculation.

Parameters:

prediction - Predicted feature

label - true label.

Returns:

Loss gradient.