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/* ==========================================
* JGraphT : a free Java graph-theory library
* ==========================================
*
* Project Info: http://jgrapht.sourceforge.net/
* Project Creator: Barak Naveh (http://sourceforge.net/users/barak_naveh)
*
* (C) Copyright 2003-2008, by Barak Naveh and Contributors.
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
*/
/* ---------------------
* VertexCoversTest.java
* ---------------------
* (C) Copyright 2003-2008, by Linda Buisman and Contributors.
*
* Original Author: Linda Buisman
* Contributor(s): Barak Naveh
*
* $Id: VertexCoversTest.java 645 2008-09-30 19:44:48Z perfecthash $
*
* Changes
* -------
* 06-Nov-2003 : Initial revision (LB);
* 10-Nov-2003 : Adapted to VertexCovers (BN);
*
*/
package org.jgrapht.alg;
import java.util.*;
import junit.framework.*;
import org.jgrapht.*;
import org.jgrapht.graph.*;
/**
* Tests the vertex cover algorithms.
*
* @author Linda Buisman
* @since Nov 6, 2003
*/
public class VertexCoversTest
extends TestCase
{
//~ Static fields/initializers ---------------------------------------------
private static final int TEST_GRAPH_SIZE = 200;
private static final int TEST_REPEATS = 20;
//~ Methods ----------------------------------------------------------------
/**
* .
*/
public void testFind2ApproximationCover()
{
for (int i = 0; i < TEST_REPEATS; i++) {
Graph<Integer, DefaultEdge> g = createRandomGraph();
assertTrue(
isCover(VertexCovers.find2ApproximationCover(g), g));
}
}
/**
* .
*/
public void testFindGreedyCover()
{
for (int i = 0; i < TEST_REPEATS; i++) {
Graph<Integer, DefaultEdge> g = createRandomGraph();
Set<Integer> c =
VertexCovers.findGreedyCover(
Graphs.undirectedGraph(g));
assertTrue(isCover(c, g));
}
}
/**
* Checks if the specified vertex set covers every edge of the graph. Uses
* the definition of Vertex Cover - removes every edge that is incident on a
* vertex in vertexSet. If no edges are left, vertexSet is a vertex cover
* for the specified graph.
*
* @param vertexSet the vertices to be tested for covering the graph.
* @param g the graph to be covered.
*
* @return
*/
private boolean isCover(
Set<Integer> vertexSet,
Graph<Integer, DefaultEdge> g)
{
Set<DefaultEdge> uncoveredEdges = new HashSet<DefaultEdge>(g.edgeSet());
for (Iterator<Integer> i = vertexSet.iterator(); i.hasNext();) {
uncoveredEdges.removeAll(g.edgesOf(i.next()));
}
return uncoveredEdges.size() == 0;
}
/**
* Create a random graph of TEST_GRAPH_SIZE nodes.
*
* @return
*/
private Graph<Integer, DefaultEdge> createRandomGraph()
{
// TODO: move random graph generator to be under GraphGenerator
// framework.
Pseudograph<Integer, DefaultEdge> g =
new Pseudograph<Integer, DefaultEdge>(DefaultEdge.class);
for (int i = 0; i < TEST_GRAPH_SIZE; i++) {
g.addVertex(new Integer(i));
}
List<Integer> vertices = new ArrayList<Integer>(g.vertexSet());
// join every vertex with a random number of other vertices
for (int source = 0; source < TEST_GRAPH_SIZE; source++) {
int numEdgesToCreate =
((int) Math.random() * TEST_GRAPH_SIZE / 2) + 1;
for (int j = 0; j < numEdgesToCreate; j++) {
// find a random vertex to join to
int target = (int) Math.floor(Math.random() * TEST_GRAPH_SIZE);
g.addEdge(vertices.get(source), vertices.get(target));
}
}
return g;
}
}
// End VertexCoversTest.java
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