package com.github.neuralnetworks.training.events;
import java.util.Set;
import com.github.neuralnetworks.architecture.Layer;
import com.github.neuralnetworks.architecture.NeuralNetwork;
import com.github.neuralnetworks.calculation.OutputError;
import com.github.neuralnetworks.calculation.ValuesProvider;
import com.github.neuralnetworks.events.TrainingEvent;
import com.github.neuralnetworks.events.TrainingEventListener;
import com.github.neuralnetworks.training.OneStepTrainer;
import com.github.neuralnetworks.training.TrainingInputData;
import com.github.neuralnetworks.training.TrainingInputProvider;
import com.github.neuralnetworks.util.UniqueList;
/**
* Listener for early stopping of the training
*/
public class EarlyStoppingListener implements TrainingEventListener {
private static final long serialVersionUID = 1L;
/**
* input provider for the cross-validation data
*/
private TrainingInputProvider inputProvider;
/**
* how much minibatches before each training
*/
private int validationFrequency;
/**
* What error is considered acceptable to stop
*/
private float acceptanceError;
private boolean isTraining;
public EarlyStoppingListener(TrainingInputProvider inputProvider, int validationFrequency, float acceptanceError) {
super();
this.validationFrequency = validationFrequency;
this.inputProvider = inputProvider;
this.acceptanceError = acceptanceError;
}
@Override
public void handleEvent(TrainingEvent event) {
if (event instanceof TrainingStartedEvent) {
isTraining = true;
} else if (event instanceof TrainingFinishedEvent) {
isTraining = false;
} else if (event instanceof MiniBatchFinishedEvent && isTraining) {
MiniBatchFinishedEvent mbe = (MiniBatchFinishedEvent) event;
if (mbe.getBatchCount() % validationFrequency == 0) {
OneStepTrainer<?> t = (OneStepTrainer<?>) event.getSource();
NeuralNetwork n = t.getNeuralNetwork();
if (n.getLayerCalculator() != null) {
Set<Layer> calculatedLayers = new UniqueList<>();
TrainingInputData input = null;
OutputError outputError = t.getOutputError();
outputError.reset();
inputProvider.reset();
while ((input = inputProvider.getNextInput()) != null) {
calculatedLayers.clear();
calculatedLayers.add(n.getInputLayer());
ValuesProvider vp = mbe.getResults();
if (vp == null) {
vp = new ValuesProvider();
}
vp.addValues(n.getInputLayer(), input.getInput());
n.getLayerCalculator().calculate(n, n.getOutputLayer(), calculatedLayers, vp);
outputError.addItem(vp.getValues(n.getOutputLayer()), input.getTarget());
}
float e = outputError.getTotalNetworkError();
if (e <= acceptanceError) {
System.out.println("Stopping at error " + e + " (" + (e * 100) + "%) for " + mbe.getBatchCount() + " minibatches");
t.stopTraining();
}
}
}
}
}
}