All Downloads are FREE. Search and download functionalities are using the official Maven repository.

org.jgrapht.nio.graph6.Graph6Sparse6Importer Maven / Gradle / Ivy

The newest version!
/*
 * (C) Copyright 2019-2023, by Dimitrios Michail and Contributors. 
 *
 * JGraphT : a free Java graph-theory library
 *
 * See the CONTRIBUTORS.md file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0, or the
 * GNU Lesser General Public License v2.1 or later
 * which is available at
 * http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR LGPL-2.1-or-later
 */
package org.jgrapht.nio.graph6;

import org.jgrapht.*;
import org.jgrapht.alg.util.*;
import org.jgrapht.nio.*;

import java.io.*;
import java.util.*;
import java.util.function.*;

/**
 * Importer which reads graphs in graph6 or sparse6 format.
 * 
 * 

* A description of the format can be found * here. graph6 and sparse6 are * formats for storing undirected graphs in a compact manner, using only printable ASCII characters. * Files in these formats have text format and contain one line per graph. graph6 is suitable for * small graphs, or large dense graphs. sparse6 is more space-efficient for large sparse graphs. * Typically, files storing graph6 graphs have the 'g6' extension. Similarly, files storing sparse6 * graphs have a 's6' file extension. sparse6 graphs support loops and multiple edges, graph6 graphs * do not. * *

* Note that a g6/s6 string may contain backslashes '\'. Thus, escaping is required. E.g. * *

 * ":?@MnDA\oi"
 * 
* * may result in undefined behavior. This should have been: * *
 * ":?@MnDA\\oi"
 * 
* *

* The graph vertices and edges are build using the corresponding graph suppliers. The id of the * vertices in the original file are reported as a vertex attribute named "ID". Note, however, that * in this file format the identifiers from the input files are always going to be integers starting * from zero, as the format does not retain such information in order to achieve compactness. * *

* The default behavior of the importer is to use the graph vertex supplier in order to create * vertices. The user can also bypass vertex creation by providing a custom vertex factory method * using {@link #setVertexFactory(Function)}. The factory method is responsible to create a new * graph vertex given the vertex identifier read from file. * * @author Dimitrios Michail * * @param graph vertex type * @param graph edge type */ public class Graph6Sparse6Importer extends BaseEventDrivenImporter implements GraphImporter { /** * Default key used for vertex ID. */ public static final String DEFAULT_VERTEX_ID_KEY = "ID"; private Function vertexFactory; /** * Construct a new importer */ public Graph6Sparse6Importer() { super(); } /** * Get the user custom vertex factory. This is null by default and the graph supplier is used * instead. * * @return the user custom vertex factory */ public Function getVertexFactory() { return vertexFactory; } /** * Set the user custom vertex factory. The default behavior is being null in which case the * graph vertex supplier is used. * * If supplied the vertex factory is called every time a new vertex is encountered in the file. * The method is called with parameter the vertex identifier from the file and should return the * actual graph vertex to add to the graph. * * @param vertexFactory a vertex factory */ public void setVertexFactory(Function vertexFactory) { this.vertexFactory = vertexFactory; } /** * Import a graph. * *

* The provided graph must be able to support the features of the graph that is read. For * example if the file contains self-loops then the graph provided must also support self-loops. * The same for multiple edges. * * @param graph the output graph * @param input the input reader * @throws ImportException in case an error occurs, such as I/O or parse error */ @Override public void importGraph(Graph graph, Reader input) { Graph6Sparse6EventDrivenImporter genericImporter = new Graph6Sparse6EventDrivenImporter(); Consumers consumers = new Consumers(graph); genericImporter.addVertexConsumer(consumers.vertexConsumer); genericImporter.addEdgeConsumer(consumers.edgeConsumer); genericImporter.importInput(input); } private class Consumers { private Graph graph; private Map map; public Consumers(Graph graph) { this.graph = graph; this.map = new HashMap(); } public final Consumer vertexConsumer = (t) -> { if (map.containsKey(t)) { throw new ImportException("Node " + t + " reported twice"); } V v; if (vertexFactory != null) { v = vertexFactory.apply(t); graph.addVertex(v); } else { v = graph.addVertex(); } map.put(t, v); /* * Notify the first time we create the node. */ notifyVertex(v); notifyVertexAttribute(v, DEFAULT_VERTEX_ID_KEY, DefaultAttribute.createAttribute(t)); }; public final Consumer> edgeConsumer = (p) -> { int source = p.getFirst(); V from = map.get(p.getFirst()); if (from == null) { throw new ImportException("Node " + source + " does not exist"); } int target = p.getSecond(); V to = map.get(target); if (to == null) { throw new ImportException("Node " + target + " does not exist"); } E e = graph.addEdge(from, to); notifyEdge(e); }; } }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy