/* This file is part of the Joshua Machine Translation System.
*
* Joshua 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
*/
package joshua.decoder.ff;
import joshua.decoder.ff.tm.Rule;
/**
*
* @author Zhifei Li, <zhifei.work@gmail.com>
* @version $LastChangedDate: 2010-02-01 08:21:59 -0600 (Mon, 01 Feb 2010) $
*/
public final class WordPenaltyFF extends DefaultStatelessFF {
private static final double OMEGA = - Math.log10(Math.E);//-0.435
public WordPenaltyFF(int featureID, double weight) {
super(weight, -1, featureID); //TODO: owner
}
/**Each additional word gets a penalty.
* The more number of words, the more negative.
* So, to encourage longer sentence, we should have
* a negative weight on the feature*/
public double estimateLogP(final Rule rule, int sentID) {
//we do not check for owner because we want this feature used for all the time, e.g., under oov_owner case
//TODO: why not check the owner
/*if (this.owner == rule.owner) {
return OMEGA * (rule.english.length - rule.arity);
} else {
return 0.0;
}*/
return OMEGA * (rule.getEnglish().length - rule.getArity());
}
}