featuretypefilter.java

一个很好的LIBSVM的JAVA源码。对于要研究和改进SVM算法的学者。可以参考。来自数据挖掘工具YALE工具包。

/*
 *  YALE - Yet Another Learning Environment
 *  Copyright (C) 2001-2004
 *      Simon Fischer, Ralf Klinkenberg, Ingo Mierswa, 
 *          Katharina Morik, Oliver Ritthoff
 *      Artificial Intelligence Unit
 *      Computer Science Department
 *      University of Dortmund
 *      44221 Dortmund,  Germany
 *  email: [e-mail]
 *  web:   http://yale.cs.uni-dortmund.de/
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as 
 *  published by the Free Software Foundation; either version 2 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
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU 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 edu.udo.cs.yale.operator.preprocessing;

import edu.udo.cs.yale.operator.UserError;
import edu.udo.cs.yale.operator.OperatorException;
import edu.udo.cs.yale.operator.parameter.*;
import edu.udo.cs.yale.example.ExampleSet;
import edu.udo.cs.yale.example.Attribute;
import edu.udo.cs.yale.tools.Ontology;
import edu.udo.cs.yale.tools.LogService;

import java.util.List;

/**
 * This operator switches off all features whose type matches the one given in 
 * the parameter <code>skip_features_of_type</code>. This can be useful
 * e.g. for learning schemes that can handle only nominal attributes.
 *
 *  @version $Id: FeatureTypeFilter.java,v 1.3 2004/09/14 08:39:07 ingomierswa Exp $
 */
public class FeatureTypeFilter extends FeatureFilter {
    private String whichType; // holds the feature type which to leave out

    /**
     * Implements the method required by the superclass. For features whose type
     * is a subtype of the one given as a parameter for this operator,
     * TRUE is returned (otherwise FALSE). If no parameter was provided, FALSE is
     * always returned, so no feature is switched off.
     *
     * @param theFeature Feature to check.
     * @return TRUE if this feature should <b>not</b> be active in the output example
     *          set of this operator. FALSE otherwise.
     */
    public boolean switchOffFeature(Attribute theFeature) throws OperatorException {
	String whichType = getParameterAsString("skip_features_of_type");
        if (Ontology.ATTRIBUTE_VALUE_TYPE.mapName(whichType) == Ontology.NO_PARENT) {
	    throw new UserError(this, 112, whichType);
        }
        if (Ontology.ATTRIBUTE_VALUE_TYPE.isA(theFeature.getValueType(), Ontology.ATTRIBUTE_VALUE_TYPE.mapName(whichType))) {
	    return true;  
	}
        return false;
    }

    public List getParameterTypes() {
	List types = super.getParameterTypes();
	types.add(new ParameterTypeString("skip_features_of_type", "All features of this type will be deselected off.", false));
	return types;
    }

}