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Java example source code file (GraphVertex.java)

This example Java source code file (GraphVertex.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

graphvertex, indarray, layer, pair, serializable, string, vertexindices

The GraphVertex.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;

import org.deeplearning4j.berkeley.Pair;
import org.deeplearning4j.nn.api.Layer;
import org.deeplearning4j.nn.gradient.Gradient;
import org.nd4j.linalg.api.ndarray.INDArray;

import java.io.Serializable;

/** A GraphVertex is a vertex in the computation graph. It may contain Layer, or define some arbitrary forward/backward pass
 * behaviour based on the inputs.<br>
 * The purposes of GraphVertex instances are as follows:
 * 1. To track the (local) network connection structure: i.e., a GraphVertex knows about the vertices on the input and output sides
 * 2. To store intermediate results (activations and epsilons)
 * 3. To allow forward pass and backward pass to be conducted, once the intermediate results are set
 * @author Alex Black
 */
public interface GraphVertex extends Serializable {

    /**Get the name/label of the GraphVertex
     */
    String getVertexName();

    /** Get the index of the GraphVertex */
    int getVertexIndex();

    /** Get the number of input arrays. For example, a Layer may have only one input array, but in general a GraphVertex
     * may have an arbtrary (>=1) number of input arrays (for example, from multiple other layers)
     */
    int getNumInputArrays();

    /** Get the number of outgoing connections from this GraphVertex. A GraphVertex may only have a single output (for
     * example, the activations out of a layer), but this output may be used as the input to an arbitrary number of other
     * GraphVertex instances. This method returns the number of GraphVertex instances the output of this GraphVertex is input for.
     */
    int getNumOutputConnections();

    /**A representation of the vertices that are inputs to this vertex (inputs duing forward pass)<br>
     * Specifically, if inputVertices[X].getVertexIndex() = Y, and inputVertices[X].getVertexEdgeNumber() = Z
     * then the Zth output connection (see {@link #getNumOutputConnections()} of vertex Y is the Xth input to this vertex
     */
    VertexIndices[] getInputVertices();

    /** Sets the input vertices.
     * @see #getInputVertices()
     */
    void setInputVertices(VertexIndices[] inputVertices);

    /**A representation of the vertices that this vertex is connected to (outputs duing forward pass)
     * Specifically, if outputVertices[X].getVertexIndex() = Y, and outputVertices[X].getVertexEdgeNumber() = Z
     * then the Xth output of this vertex is connected to the Zth input of vertex Y
     */
    VertexIndices[] getOutputVertices();

    /** set the output vertices.
     * @see #getOutputVertices()
     */
    void setOutputVertices(VertexIndices[] outputVertices);

    /** whether the GraphVertex contains a {@link Layer} object or not */
    boolean hasLayer();

    /** Whether the GraphVertex is an input vertex */
    boolean isInputVertex();

    /** Whether the GraphVertexis an output vertex */
    boolean isOutputVertex();

    /** Get the Layer (if any). Returns null if {@link #hasLayer()} == false */
    Layer getLayer();

    /** Set the input activations.
     *
     * @param inputNumber Must be in range 0 to {@link #getNumInputArrays()}-1
     * @param input The input array
     */
    void setInput(int inputNumber, INDArray input);

    /** Set the errors (epsilons) for this GraphVertex */
    void setError(int errorNumber, INDArray error);

    /** Clear the internal state (if any) of the GraphVertex. For example, any stored inputs/errors */
    void clear();

    /** Whether the GraphVertex can do forward pass. Typically, this is just whether all inputs are set. */
    boolean canDoForward();

    /** Whether the GraphVertex can do backward pass. Typically, this is just whether all errors/epsilons are set */
    boolean canDoBackward();

    /** Do forward pass using the stored inputs
     * @param training if true: forward pass at training time. If false: forward pass at test time
     * @return The output (for example, activations) of the GraphVertex
     */
    INDArray doForward(boolean training);

    /** Do backward pass
     * @param tbptt If true: do backprop using truncated BPTT
     * @return The gradients (may be null), and the errors/epsilons for all inputs to this GraphVertex
     */
    Pair<Gradient,INDArray[]> doBackward(boolean tbptt);

    /** Get the array of inputs previously set for this GraphVertex */
    INDArray[] getInputs();

    /** Get the array of errors previously set for this GraphVertex */
    INDArray[] getErrors();

    /** Set all inputs for this GraphVertex
     * @see #setInput(int, INDArray)
     */
    void setInputs(INDArray... inputs);

    /** Set all errors/epsilons for this GraphVertex
     * @see #setError(int, INDArray)
     */
    void setErrors(INDArray... errors);

    /**
     * See {@link Layer#setBackpropGradientsViewArray(INDArray)}
     * @param backpropGradientsViewArray
     */
    void setBackpropGradientsViewArray(INDArray backpropGradientsViewArray);
}

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