org.jgrapht.nio.dimacs.DIMACSExporter Maven / Gradle / Ivy
/*
* (C) Copyright 2017-2021, 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.dimacs;
import org.jgrapht.*;
import org.jgrapht.nio.*;
import java.io.*;
import java.util.*;
import java.util.function.*;
/**
* Exports a graph into DIMACS format.
*
*
* For a description of the format see
* http://dimacs.rutgers.edu/Challenges. Note that there are a lot of different formats based on
* each different challenge, see {@link DIMACSFormat} for the supported formats. The exporter uses
* the {@link DIMACSFormat#MAX_CLIQUE} by default.
*
* @param the graph vertex type
* @param the graph edge type
*
* @author Dimitrios Michail
*/
public class DIMACSExporter
extends
BaseExporter
implements
GraphExporter
{
/**
* The default format used by the exporter.
*/
public static final DIMACSFormat DEFAULT_DIMACS_FORMAT = DIMACSFormat.MAX_CLIQUE;
private static final String HEADER = "Generated using the JGraphT library";
private final Set parameters;
private DIMACSFormat format;
/**
* Parameters that affect the behavior of the {@link DIMACSExporter} exporter.
*/
public enum Parameter
{
/**
* If set the exporter outputs edge weights
*/
EXPORT_EDGE_WEIGHTS,
}
/**
* Constructs a new exporter.
*/
public DIMACSExporter()
{
this(new IntegerIdProvider<>());
}
/**
* Constructs a new exporter with a given vertex ID provider.
*
* @param vertexIdProvider for generating vertex IDs. Must not be null.
*/
public DIMACSExporter(Function vertexIdProvider)
{
this(vertexIdProvider, DEFAULT_DIMACS_FORMAT);
}
/**
* Constructs a new exporter with a given vertex ID provider.
*
* @param vertexIdProvider for generating vertex IDs. Must not be null.
* @param format the format to use
*/
public DIMACSExporter(Function vertexIdProvider, DIMACSFormat format)
{
super(vertexIdProvider);
this.format = Objects.requireNonNull(format, "Format cannot be null");
this.parameters = new HashSet<>();
}
@Override
public void exportGraph(Graph g, Writer writer)
{
PrintWriter out = new PrintWriter(writer);
out.println("c");
out.println("c SOURCE: " + HEADER);
out.println("c");
out
.println(
"p " + format.getProblem() + " " + g.vertexSet().size() + " " + g.edgeSet().size());
boolean exportEdgeWeights = parameters.contains(Parameter.EXPORT_EDGE_WEIGHTS);
for (E edge : g.edgeSet()) {
out.print(format.getEdgeDescriptor());
out.print(" ");
out.print(getVertexId(g.getEdgeSource(edge)));
out.print(" ");
out.print(getVertexId(g.getEdgeTarget(edge)));
if (exportEdgeWeights) {
out.print(" ");
out.print(Double.toString(g.getEdgeWeight(edge)));
}
out.println();
}
out.flush();
}
/**
* Return if a particular parameter of the exporter is enabled
*
* @param p the parameter
* @return {@code true} if the parameter is set, {@code false} otherwise
*/
public boolean isParameter(Parameter p)
{
return parameters.contains(p);
}
/**
* Set the value of a parameter of the exporter
*
* @param p the parameter
* @param value the value to set
*/
public void setParameter(Parameter p, boolean value)
{
if (value) {
parameters.add(p);
} else {
parameters.remove(p);
}
}
/**
* Get the format of the exporter
*
* @return the format of the exporter
*/
public DIMACSFormat getFormat()
{
return format;
}
/**
* Set the format of the exporter
*
* @param format the format to use
*/
public void setFormat(DIMACSFormat format)
{
this.format = Objects.requireNonNull(format, "Format cannot be null");
}
}