org.jgrapht.generate.CompleteGraphGenerator Maven / Gradle / Ivy
/*
* (C) Copyright 2003-2023, by Tim Shearouse 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.generate;
import org.jgrapht.*;
import java.util.*;
/**
* Generates a complete graph of any size.
*
*
* A complete graph is a graph where every vertex shares an edge with every other vertex. If it is a
* directed graph, then edges must always exist in both directions.
*
* @param the graph vertex type
* @param the graph edge type
*
* @author Tim Shearouse
*/
public class CompleteGraphGenerator
implements GraphGenerator
{
private final int size;
/**
* Construct a new CompleteGraphGenerator.
*
* The generator will first add {@code size} nodes to the target graph when invoking
* {@link #generateGraph(Graph, Map)}. Next, a complete graph is generated on all nodes
* present in the target graph, including any nodes that were already present in the target
* graph.
*
* @param size number of vertices that will be added to the graph
* @throws IllegalArgumentException if the specified size is negative
*/
public CompleteGraphGenerator(int size)
{
if (size < 0)
throw new IllegalArgumentException("size must be non-negative");
this.size = size;
}
/**
* Construct a new CompleteGraphGenerator.
*
* A complete graph will be generated using the vertices already present in the target graph
* when invoking {@link #generateGraph(Graph, Map)}
*/
public CompleteGraphGenerator()
{
size = 0;
}
/**
* {@inheritDoc}
*/
@Override
public void generateGraph(Graph target, Map resultMap)
{
/*
* Ensure directed or undirected
*/
GraphTests.requireDirectedOrUndirected(target);
boolean isDirected = target.getType().isDirected();
/*
* Add vertices
*/
for (int i = 0; i < size; i++)
target.addVertex();
/*
* Add edges
*/
List nodes = new ArrayList<>(target.vertexSet());
for (int i = 0; i < nodes.size(); i++) {
for (int j = i + 1; j < nodes.size(); j++) {
V v = nodes.get(i);
V u = nodes.get(j);
target.addEdge(v, u);
if (isDirected) {
target.addEdge(u, v);
}
}
}
}
}