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Java example source code file (DuplicateToTimeSeriesVertex.java)

This example Java source code file (DuplicateToTimeSeriesVertex.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.

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Java - Java tags/keywords

basegraphvertex, duplicatetotimeseriesvertex, illegalargumentexception, indarray, indarrayindex, invalid, layer, override, pair, runtimeexception, string, vertexindices

The DuplicateToTimeSeriesVertex.java Java example source code

/*
 *
 *  * Copyright 2016 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.graph.vertex.impl.rnn;

import org.deeplearning4j.berkeley.Pair;
import org.deeplearning4j.nn.api.Layer;
import org.deeplearning4j.nn.gradient.Gradient;
import org.deeplearning4j.nn.graph.ComputationGraph;
import org.deeplearning4j.nn.graph.vertex.BaseGraphVertex;
import org.deeplearning4j.nn.graph.vertex.VertexIndices;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.factory.Nd4j;
import org.nd4j.linalg.indexing.INDArrayIndex;
import org.nd4j.linalg.indexing.NDArrayIndex;

/**DuplicateToTimeSeriesVertex is a vertex that goes from 2d activations to a 3d time series activations, by means of
 * duplication. That is, given a 2d input with shape [numExamples,nIn] duplicate each row to give output of
 * [numExamples,nIn,timeSeriesLength], where the activations are the same for all time steps.<br>
 * This method is used for example in sequence to sequence models.<br>
 * <b>Note: The length of the output time series (number of time steps) is determined by means of referencing one of the
 * inputs in the ComputationGraph. That is: Because the length of the time series may differ at runtime, we generally want the number
 * of time steps to match some other input; here, we are specifying the length of the output time series to be the same as
 * one of the input time series<br>
 * @author Alex Black
 */
public class DuplicateToTimeSeriesVertex extends BaseGraphVertex {

    private String inputName;
    private int inputVertexIndex;

    public DuplicateToTimeSeriesVertex(ComputationGraph graph, String name, int vertexIndex, String inputVertexName){
        this(graph,name,vertexIndex,null,null,inputVertexName);
    }

    public DuplicateToTimeSeriesVertex(ComputationGraph graph, String name, int vertexIndex, VertexIndices[] inputVertices,
                                       VertexIndices[] outputVertices, String inputName) {
        super(graph, name, vertexIndex, inputVertices, outputVertices);
        this.inputName = inputName;
        this.inputVertexIndex = graph.getConfiguration().getNetworkInputs().indexOf(inputName);
        if(inputVertexIndex == -1)  throw new IllegalArgumentException("Invalid input name: \"" + inputName + "\" not found in list "
                + "of network inputs (" + graph.getConfiguration().getNetworkInputs() + ")");
    }

    @Override
    public boolean hasLayer() {
        return false;
    }

    @Override
    public boolean isOutputVertex() {
        return false;
    }

    @Override
    public Layer getLayer() {
        return null;
    }

    @Override
    public INDArray doForward(boolean training) {

        //First: work out the time series length
        int tsLength = graph.getInput(inputVertexIndex).size(2);
        int[] outShape = new int[]{inputs[0].size(0),inputs[0].size(1),tsLength};

        INDArray out = Nd4j.create(outShape);
        for( int i=0; i<tsLength; i++ ){
            out.put(new INDArrayIndex[]{NDArrayIndex.all(),NDArrayIndex.all(), NDArrayIndex.point(i)},inputs[0]);
        }
        return out;
    }

    @Override
    public Pair<Gradient, INDArray[]> doBackward(boolean tbptt) {
        //Because we duplicated for each time step: simply need to sum along time for errors/epsilons
        return new Pair<>(null,new INDArray[]{epsilons[0].sum(2)});
    }

    @Override
    public void setBackpropGradientsViewArray(INDArray backpropGradientsViewArray) {
        if(backpropGradientsViewArray != null) throw new RuntimeException("Vertex does not have gradients; gradients view array cannot be set here");
    }

    @Override
    public String toString(){
        return "DuplicateToTimeSeriesVertex(inputName=" + inputName + ")";
    }
}

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