CenterLossOutputLayer.java

/*-
 *
 *  * Copyright 2015 Skymind,Inc.
 *  *
 *  *    Licensed under the Apache License, Version 2.0 (the "License");
 *  *    you may not use this file except in compliance with the License.
 *  *    You may obtain a copy of the License at
 *  *
 *  *        http://www.apache.org/licenses/LICENSE-2.0
 *  *
 *  *    Unless required by applicable law or agreed to in writing, software
 *  *    distributed under the License is distributed on an "AS IS" BASIS,
 *  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  *    See the License for the specific language governing permissions and
 *  *    limitations under the License.
 *
 */

package org.deeplearning4j.nn.conf.layers;

import lombok.Data;
import lombok.EqualsAndHashCode;
import lombok.NoArgsConstructor;
import lombok.ToString;
import org.deeplearning4j.nn.api.Layer;
import org.deeplearning4j.nn.api.ParamInitializer;
import org.deeplearning4j.nn.conf.NeuralNetConfiguration;
import org.deeplearning4j.nn.conf.Updater;
import org.deeplearning4j.nn.params.CenterLossParamInitializer;
import org.deeplearning4j.nn.params.DefaultParamInitializer;
import org.deeplearning4j.optimize.api.IterationListener;
import org.deeplearning4j.util.LayerValidation;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.learning.config.IUpdater;
import org.nd4j.linalg.learning.config.NoOp;
import org.nd4j.linalg.lossfunctions.ILossFunction;
import org.nd4j.linalg.lossfunctions.LossFunctions.LossFunction;

import java.util.Collection;
import java.util.Map;

/**
 * Center loss is similar to triplet loss except that it enforces
 * intraclass consistency and doesn't require feed forward of multiple
 * examples. Center loss typically converges faster for training
 * ImageNet-based convolutional networks.
 *
 * "If example x is in class Y, ensure that embedding(x) is close to
 * average(embedding(y)) for all examples y in Y"
 *
 * @author Justin Long (@crockpotveggies)
 * @author Alex Black (@AlexDBlack)
 */
@Data
@NoArgsConstructor
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public class CenterLossOutputLayer extends BaseOutputLayer {
    protected double alpha;
    protected double lambda;
    protected boolean gradientCheck;

    protected CenterLossOutputLayer(Builder builder) {
        super(builder);
        this.alpha = builder.alpha;
        this.lambda = builder.lambda;
        this.gradientCheck = builder.gradientCheck;
    }

    @Override
    public Layer instantiate(NeuralNetConfiguration conf, Collection<IterationListener> iterationListeners,
                    int layerIndex, INDArray layerParamsView, boolean initializeParams) {
        LayerValidation.assertNInNOutSet("CenterLossOutputLayer", getLayerName(), layerIndex, getNIn(), getNOut());

        Layer ret = new org.deeplearning4j.nn.layers.training.CenterLossOutputLayer(conf);
        ret.setListeners(iterationListeners);
        ret.setIndex(layerIndex);
        ret.setParamsViewArray(layerParamsView);
        Map<String, INDArray> paramTable = initializer().init(conf, layerParamsView, initializeParams);
        ret.setParamTable(paramTable);
        ret.setConf(conf);
        return ret;
    }

    @Override
    public ParamInitializer initializer() {
        return CenterLossParamInitializer.getInstance();
    }

    @Override
    @Deprecated
    public Updater getUpdaterByParam(String paramName) {
        // center loss utilizes alpha directly for this so any updater can be used for other layers
        switch (paramName) {
            case CenterLossParamInitializer.CENTER_KEY:
                return Updater.NONE;
            default:
                return updater;
        }
    }

    @Override
    public IUpdater getIUpdaterByParam(String paramName) {
        // center loss utilizes alpha directly for this so any updater can be used for other layers
        switch (paramName) {
            case CenterLossParamInitializer.CENTER_KEY:
                return new NoOp();
            default:
                return iUpdater;
        }
    }

    @Override
    public double getLearningRateByParam(String paramName) {
        switch (paramName) {
            case CenterLossParamInitializer.WEIGHT_KEY:
                return learningRate;
            case CenterLossParamInitializer.BIAS_KEY:
                if (!Double.isNaN(biasLearningRate)) {
                    //Bias learning rate has been explicitly set
                    return biasLearningRate;
                } else {
                    return learningRate;
                }
            case CenterLossParamInitializer.CENTER_KEY:
                return 0;
            default:
                throw new IllegalStateException("Unknown parameter: \"" + paramName + "\"");
        }
    }

    @Override
    public double getL1ByParam(String paramName) {
        switch (paramName) {
            case CenterLossParamInitializer.WEIGHT_KEY:
                return l1;
            case CenterLossParamInitializer.BIAS_KEY:
                return l1Bias;
            case CenterLossParamInitializer.CENTER_KEY:
                return 0.0;
            default:
                throw new IllegalStateException("Unknown parameter: \"" + paramName + "\"");
        }
    }

    @Override
    public double getL2ByParam(String paramName) {
        switch (paramName) {
            case CenterLossParamInitializer.WEIGHT_KEY:
                return l2;
            case CenterLossParamInitializer.BIAS_KEY:
                return l2Bias;
            case CenterLossParamInitializer.CENTER_KEY:
                return 0.0;
            default:
                throw new IllegalStateException("Unknown parameter: \"" + paramName + "\"");
        }
    }

    public double getAlpha() {
        return alpha;
    }

    public double getLambda() {
        return lambda;
    }

    public boolean getGradientCheck() {
        return gradientCheck;
    }

    @NoArgsConstructor
    public static class Builder extends BaseOutputLayer.Builder<Builder> {
        protected double alpha = 0.05;
        protected double lambda = 2e-4;
        protected boolean gradientCheck = false;

        public Builder(LossFunction lossFunction) {
            super.lossFunction(lossFunction);
        }

        public Builder(ILossFunction lossFunction) {
            this.lossFn = lossFunction;
        }

        public Builder alpha(double alpha) {
            this.alpha = alpha;
            return this;
        }

        public Builder lambda(double lambda) {
            this.lambda = lambda;
            return this;
        }

        public Builder gradientCheck(boolean isGradientCheck) {
            this.gradientCheck = isGradientCheck;
            return this;
        }

        @Override
        @SuppressWarnings("unchecked")
        public CenterLossOutputLayer build() {
            return new CenterLossOutputLayer(this);
        }
    }
}