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Java example source code file (MultiLayerUpdater.java)

This example Java source code file (MultiLayerUpdater.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

defaultgradient, equalsandhashcode, gradient, illegalstateexception, invalid, mulilayernetwork, multilayernetwork, multilayerupdater, multilayerupdateraggregator, override, string, updater, util

The MultiLayerUpdater.java Java example source code

package org.deeplearning4j.nn.updater;

import java.util.Map;

import lombok.EqualsAndHashCode;
import lombok.Getter;
import org.deeplearning4j.nn.api.Layer;
import org.deeplearning4j.nn.api.Updater;
import org.deeplearning4j.nn.gradient.DefaultGradient;
import org.deeplearning4j.nn.gradient.Gradient;
import org.deeplearning4j.nn.multilayer.MultiLayerNetwork;
import org.deeplearning4j.nn.updater.aggregate.UpdaterAggregator;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.learning.GradientUpdater;

/**MultiLayerUpdater: Gradient updater for MultiLayerNetworks.
 * Expects backprop gradients for all layers to be in single Gradient object,
 * keyed by "0_b", "1_w" etc., as per MultiLayerNetwork.backward()
public class MultiLayerUpdater implements Updater {
	private final Updater[] layerUpdaters;
	public MultiLayerUpdater( MultiLayerNetwork network ){
		Layer[] layers = network.getLayers();
		layerUpdaters = new Updater[layers.length];
		for( int i=0; i<layers.length; i++ ){
			layerUpdaters[i] = UpdaterCreator.getUpdater(layers[i]);

	public MultiLayerUpdater(MultiLayerUpdater updater){
		layerUpdaters = new Updater[updater.layerUpdaters.length];
		for( int i=0; i<updater.layerUpdaters.length; i++ ){
			layerUpdaters[i] = updater.layerUpdaters[i].clone();

	private MultiLayerUpdater(int size){
		layerUpdaters = new Updater[size];

	public void update(Layer layer, Gradient gradient, int iteration, int batchSize) {
		MultiLayerNetwork mln = (MultiLayerNetwork)layer;
		Gradient[] layerGradients = new Gradient[layerUpdaters.length];
		for( int i=0; i<layerGradients.length; i++)
			layerGradients[i] = new DefaultGradient();
		for(Map.Entry<String,INDArray> gradientPair : gradient.gradientForVariable().entrySet()) {
			String key = gradientPair.getKey();
			int idx = key.indexOf("_");
			if( idx == -1 ) throw new IllegalStateException("Invalid key: MuliLayerNetwork Gradient key does not have layer separator: \""+key+"\"");
			int layerIdx = Integer.parseInt(key.substring(0, idx));
			String newKey = key.substring(idx + 1);
			layerGradients[layerIdx].gradientForVariable().put(newKey, gradientPair.getValue());
		for( int i = 0; i < layerUpdaters.length; i++ ) {
			layerUpdaters[i].update(mln.getLayer(i), layerGradients[i], iteration, batchSize);

	public UpdaterAggregator getAggregator(boolean addThis) {
		MultiLayerUpdaterAggregator ag = new MultiLayerUpdaterAggregator();
		if(addThis) ag.aggregate(this);
		return ag;

	protected static class MultiLayerUpdaterAggregator implements UpdaterAggregator {

		private UpdaterAggregator[] aggregators;

		public void aggregate(Updater updater) {
			MultiLayerUpdater mlu = (MultiLayerUpdater)updater;
			if (aggregators == null) {
				aggregators = new UpdaterAggregator[mlu.layerUpdaters.length];
				for( int i=0; i<aggregators.length; i++ ){
					aggregators[i] = mlu.layerUpdaters[i].getAggregator(true);
			} else {
				if(mlu.layerUpdaters == null) return;
				for( int i=0; i<aggregators.length; i++ ){

		public void merge(UpdaterAggregator aggregator) {
			MultiLayerUpdaterAggregator mlua = (MultiLayerUpdaterAggregator)aggregator;
			if(aggregators == null){
				aggregators = mlua.aggregators;
			} else {
				if (mlua.aggregators != null) {
					for(int i=0; i<aggregators.length; i++ ){

		public Updater getUpdater() {
			MultiLayerUpdater multiLayerUpdater = new MultiLayerUpdater(aggregators.length);
			for( int i=0; i<aggregators.length; i++ ){
				multiLayerUpdater.layerUpdaters[i] = aggregators[i].getUpdater();
			return multiLayerUpdater;

	public Updater clone(){
		return new MultiLayerUpdater(this);

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