- utility for weakening alignments on ontology networks (weakening implemented)

src/fr/inrialpes/exmo/align/util/OntologyNetworkWeakener.java

+/*
+ * $Id$
+ *
+ * Copyright (C) INRIA, 2009
+ *
+ * This program 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 program 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 program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+ * USA.
+ */
+
+package fr.inrialpes.exmo.align.util;
+
+import org.semanticweb.owl.align.Alignment;
+import org.semanticweb.owl.align.AlignmentException;
+import org.semanticweb.owl.align.Cell;
+import org.semanticweb.owl.align.OntologyNetwork;
+
+import fr.inrialpes.exmo.align.impl.BasicOntologyNetwork;
+
+import java.net.URI;
+import java.util.Set;
+import java.util.Collections;
+import java.util.ArrayList;
+
+/**
+ * OntologyNetworkWeakener
+ *
+ * A utility class that transform an ontology network in one with less alignments/
+ */
+public class OntologyNetworkWeakener {
+
+    /**
+     * suppress n% of the correspondences at random in all alignments
+     */
+    public static OntologyNetwork unconnect( OntologyNetwork on, int n ){
+	return on;
+    }
+
+    /**
+     * suppress n% of the correspondences at random in all alignments
+     * n is a number between 0. and 1.
+     * Returns a brand new BasicOntologyNetwork (with new alignments and cells)
+     */
+    public static OntologyNetwork weakenAlignments( OntologyNetwork on, double n ) throws AlignmentException {
+	if ( n < 0. || n > 1. )
+	    throw new AlignmentException( "Argument must be between 0 and 1.: "+n );
+	OntologyNetwork newon = new BasicOntologyNetwork();
+	for ( URI ontouri : on.getOntologies() ){
+	    newon.addOntology( ontouri );
+	}
+	for ( Alignment al : on.getAlignments() ){
+	    Alignment newal = (Alignment)al.clone();
+	    int size = newal.nbCells();
+	    // --------------------------------------------------------------------
+	    // JE: Here is a tricky one.
+	    // Using collection schuffle randomly reorganises a list
+	    // Then choosing the fist n% and destroying them in the Set is performed
+	    // The complexity is O(copy=N)+O(shuffle=N)+n%*O(delete=N)
+	    // That's not bad... (and also avoid checking if the same nb is drawn)
+	    // But in practice other solutions may be better, like:
+	    // Generating randomly n%*N numbers between 0 and N (util.Random)
+	    // Ordering them 
+	    // Traversing the initial structure and deleting the choosen ones...
+	    // This one (deleting when traversing) is tricky in Java.
+	    // --------------------------------------------------------------------
+	    ArrayList<Cell> array = new ArrayList<Cell>( size );
+	    for ( Cell c : newal ) {
+		array.add( c );
+	    }
+	    Collections.shuffle( array );
+	    for ( int i = (int)(n*size); i > 0; i-- ){
+		newal.remCell( array.get( i ) );
+	    }
+	}
+	return newon;
+    }
+}