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Java example source code file (GraphLoader.java)

This example Java source code file (GraphLoader.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

bufferedreader, delimitededgelineprocessor, edgelineprocessor, file, filereader, graph, graphloader, ioexception, list, string, stringvertexfactory, util, v,e, vertexloader, weightededgelineprocessor

The GraphLoader.java Java example source code

package org.deeplearning4j.graph.data;

import org.deeplearning4j.graph.api.Edge;
import org.deeplearning4j.graph.api.Vertex;
import org.deeplearning4j.graph.data.impl.DelimitedEdgeLineProcessor;
import org.deeplearning4j.graph.data.impl.WeightedEdgeLineProcessor;
import org.deeplearning4j.graph.graph.Graph;
import org.deeplearning4j.graph.vertexfactory.StringVertexFactory;
import org.deeplearning4j.graph.vertexfactory.VertexFactory;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.List;

/** Utility methods for loading graphs
 *
 */
public class GraphLoader {

    /** Simple method for loading an undirected graph, where the graph is represented by a edge list with one edge
     * per line with a delimiter in between<br>
     * This method assumes that all lines in the file are of the form {@code i<delim>j} where i and j are integers
     * in range 0 to numVertices inclusive, and "<delim>" is the user-provided delimiter
     * <b>Note: this method calls {@link #loadUndirectedGraphEdgeListFile(String, int, String, boolean)} with allowMultipleEdges = true.
     * @param path Path to the edge list file
     * @param numVertices number of vertices in the graph
     * @return graph
     * @throws IOException if file cannot be read
     */
    public static Graph<String,String> loadUndirectedGraphEdgeListFile(String path, int numVertices, String delim) throws IOException {
        return loadUndirectedGraphEdgeListFile(path,numVertices,delim,true);
    }

    /** Simple method for loading an undirected graph, where the graph is represented by a edge list with one edge
     * per line with a delimiter in between<br>
     * This method assumes that all lines in the file are of the form {@code i<delim>j} where i and j are integers
     * in range 0 to numVertices inclusive, and "<delim>" is the user-provided delimiter
     * @param path Path to the edge list file
     * @param numVertices number of vertices in the graph
     * @param allowMultipleEdges If set to false, the graph will not allow multiple edges between any two vertices to exist. However,
     *                           checking for duplicates during graph loading can be costly, so use allowMultipleEdges=true when
     *                           possible.
     * @return graph
     * @throws IOException if file cannot be read
     */
    public static Graph<String,String> loadUndirectedGraphEdgeListFile(String path, int numVertices, String delim, boolean allowMultipleEdges) throws IOException {
        Graph<String,String> graph = new Graph<>(numVertices,allowMultipleEdges,new StringVertexFactory());
        EdgeLineProcessor<String> lineProcessor = new DelimitedEdgeLineProcessor(delim,false);

        try(BufferedReader br = new BufferedReader(new FileReader(new File(path)))){
            String line;
            while( (line = br.readLine()) != null ) {
                Edge<String> edge = lineProcessor.processLine(line);
                if(edge != null){
                    graph.addEdge(edge);
                }
            }
        }
        return graph;
    }

    /**Method for loading a weighted graph from an edge list file, where each edge (inc. weight) is represented by a
     * single line. Graph may be directed or undirected<br>
     * This method assumes that edges are of the format: {@code fromIndex<delim>toIndexedgeWeight} where {@code }
     * is the delimiter.
     * <b>Note: this method calls {@link #loadWeightedEdgeListFile(String, int, String, boolean, boolean, String...)} with allowMultipleEdges = true.
     * @param path Path to the edge list file
     * @param numVertices The number of vertices in the graph
     * @param delim The delimiter used in the file (typically: "," or " " etc)
     * @param directed whether the edges should be treated as directed (true) or undirected (false)
     * @param ignoreLinesStartingWith Starting characters for comment lines. May be null. For example: "//" or "#"
     * @return The graph
     * @throws IOException
     */
    public static Graph<String,Double> loadWeightedEdgeListFile(String path, int numVertices, String delim, boolean directed,
                                                                String... ignoreLinesStartingWith) throws IOException {
        return loadWeightedEdgeListFile(path,numVertices,delim,directed,true,ignoreLinesStartingWith);
    }

    /**Method for loading a weighted graph from an edge list file, where each edge (inc. weight) is represented by a
     * single line. Graph may be directed or undirected<br>
     * This method assumes that edges are of the format: {@code fromIndex<delim>toIndexedgeWeight} where {@code }
     * is the delimiter.
     * @param path Path to the edge list file
     * @param numVertices The number of vertices in the graph
     * @param delim The delimiter used in the file (typically: "," or " " etc)
     * @param directed whether the edges should be treated as directed (true) or undirected (false)
     * @param allowMultipleEdges If set to false, the graph will not allow multiple edges between any two vertices to exist. However,
     *                           checking for duplicates during graph loading can be costly, so use allowMultipleEdges=true when
     *                           possible.
     * @param ignoreLinesStartingWith Starting characters for comment lines. May be null. For example: "//" or "#"
     * @return The graph
     * @throws IOException
     */
    public static Graph<String,Double> loadWeightedEdgeListFile(String path, int numVertices, String delim, boolean directed,
                                                                boolean allowMultipleEdges, String... ignoreLinesStartingWith) throws IOException {
        Graph<String,Double> graph = new Graph<>(numVertices,allowMultipleEdges,new StringVertexFactory());
        EdgeLineProcessor<Double> lineProcessor = new WeightedEdgeLineProcessor(delim,directed,ignoreLinesStartingWith);

        try(BufferedReader br = new BufferedReader(new FileReader(new File(path)))){
            String line;
            while( (line = br.readLine()) != null ) {
                Edge<Double> edge = lineProcessor.processLine(line);
                if(edge != null){
                    graph.addEdge(edge);
                }
            }
        }
        return graph;
    }

    /** Load a graph into memory, using a given EdgeLineProcessor.
     * Assume one edge per line
     * @param path Path to the file containing the edges, one per line
     * @param lineProcessor EdgeLineProcessor used to convert lines of text into a graph (or null for comment lines etc)
     * @param vertexFactory Used to create vertices
     * @param numVertices number of vertices in the graph
     * @param allowMultipleEdges whether the graph should allow multiple edges between a given pair of vertices or not
     * @return IGraph
     */
    public static <V,E> Graph loadGraph(String path, EdgeLineProcessor lineProcessor,
                                                   VertexFactory<V> vertexFactory, int numVertices,
                                                   boolean allowMultipleEdges) throws IOException {
        Graph<V,E> graph = new Graph<>(numVertices,allowMultipleEdges,vertexFactory);

        try(BufferedReader br = new BufferedReader(new FileReader(new File(path)))){
            String line;
            while( (line = br.readLine()) != null ) {
                Edge<E> edge = lineProcessor.processLine(line);
                if(edge != null){
                    graph.addEdge(edge);
                }
            }
        }

        return graph;
    }

    /** Load graph, assuming vertices are in one file and edges are in another file.
     *
     * @param vertexFilePath Path to file containing vertices, one per line
     * @param edgeFilePath Path to the file containing edges, one per line
     * @param vertexLoader VertexLoader, for loading vertices from the file
     * @param edgeLineProcessor EdgeLineProcessor, converts text lines into edges
     * @param allowMultipleEdges whether the graph should allow (or filter out) multiple edges
     * @return IGraph loaded from files
     */
    public static <V,E> Graph loadGraph(String vertexFilePath, String edgeFilePath, VertexLoader vertexLoader,
                                                   EdgeLineProcessor<E> edgeLineProcessor, boolean allowMultipleEdges ) throws IOException {
        //Assume vertices are in one file
        //And edges are in another file

        List<Vertex vertices = vertexLoader.loadVertices(vertexFilePath);
        Graph<V,E> graph = new Graph<>(vertices,allowMultipleEdges);

        try(BufferedReader br = new BufferedReader(new FileReader(new File(edgeFilePath)))){
            String line;
            while( (line = br.readLine()) != null ) {
                Edge<E> edge = edgeLineProcessor.processLine(line);
                if(edge != null){
                    graph.addEdge(edge);
                }
            }
        }

        return graph;
    }
}

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