/* Copyright (C) 2003 Univ. of Massachusetts Amherst, Computer Science Dept.
This file is part of "MALLET" (MAchine Learning for LanguagE Toolkit).
http://www.cs.umass.edu/~mccallum/mallet
This software is provided under the terms of the Common Public License,
version 1.0, as published by http://www.opensource.org. For further
information, see the file `LICENSE' included with this distribution. */
package cc.mallet.grmm.util;
import org._3pq.jgrapht.UndirectedGraph;
import org._3pq.jgrapht.graph.SimpleGraph;
import cc.mallet.grmm.types.Factor;
import cc.mallet.grmm.types.FactorGraph;
import cc.mallet.grmm.types.VarSet;
import cc.mallet.grmm.types.Variable;
import java.util.Iterator;
/**
* Created: Dec 21, 2005
*
* @author <A HREF="mailto:casutton@cs.umass.edu>casutton@cs.umass.edu</A>
* @version $Id: Graphs.java,v 1.1 2007/10/22 21:37:58 mccallum Exp $
*/
public class Graphs {
/**
* Converts a FactorGraph into a plain graph where each Variable is a vertex,
* and two Variables are connected by an edge if they are arguments to the same factor.
* (Essentially converts an fg into an MRF structure, minus the factors.)
* @param fg
* @return a Graph
*/
public static UndirectedGraph mdlToGraph (FactorGraph fg)
{
UndirectedGraph g = new SimpleGraph ();
for (Iterator it = fg.variablesIterator (); it.hasNext ();) {
Variable var = (Variable) it.next ();
g.addVertex (var);
}
for (Iterator it = fg.factorsIterator (); it.hasNext ();) {
Factor factor = (Factor) it.next ();
VarSet varSet = factor.varSet ();
int nv = varSet.size ();
for (int i = 0; i < nv; i++) {
for (int j = i + 1; j < nv; j++) {
g.addEdge (varSet.get (i), varSet.get (j));
}
}
}
return g;
}
}