examplefilter.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.Operator;
import edu.udo.cs.yale.operator.IOObject;
import edu.udo.cs.yale.operator.OperatorException;
import edu.udo.cs.yale.operator.parameter.*;
import edu.udo.cs.yale.example.Example;
import edu.udo.cs.yale.example.ExampleSet;
import edu.udo.cs.yale.example.FilteredExampleSet;
import edu.udo.cs.yale.example.ConditionExampleReader;
import edu.udo.cs.yale.tools.LogService;

import java.util.List;

/** This operator takes an {@link ExampleSet} as input and returns a 
 *  new {@link ExampleSet} including only the {@link Example}s that fulfill a 
 *  condition.
 *  <br/>
 *  By specifying an implementation of 
 *  {@link edu.udo.cs.yale.example.Condition}
 *  and a parameter string, arbitrary filters can be applied. Users can implement
 *  their own conditions by writing a subclass of the above class and implementing a two
 *  argument constructor taking an {@link ExampleSet} and a parameter string.
 *  This parameter string is specified by the parameter <code>parameter_string</code>.
 *  <br/>
 *  For {@link edu.udo.cs.yale.example.AttributeValueFilter} the parameter string
 *  must have the form <code>attribute op value</code>, where attribute is a name of 
 *  an attribute, value is a value the attribute can take and op is one of the binary
 *  logical operators similar to the ones known from Java.<br/>
 *  For {@link edu.udo.cs.yale.example.LegalNumberCondition} the parameter string may
 *  be empty. This filter removes all examples containing attributes that have missing or
 *  illegal values.
 *
 * @version $Id: ExampleFilter.java,v 1.2 2004/08/27 11:57:44 ingomierswa Exp $
 */
public class ExampleFilter extends Operator {
    private static final Class[] INPUT_CLASSES = { ExampleSet.class };
    private static final Class[] OUTPUT_CLASSES = { ExampleSet.class };

    private int dataRowType;

    public IOObject[] apply() throws OperatorException {
        // get the input example set
	ExampleSet inputSet = (ExampleSet)getInput(ExampleSet.class);

        LogService.logMessage(getName()+": input set has " + inputSet.getSize() + " examples.", 
			      LogService.STATUS);

	String className = getParameterAsString("condition_class");
	String parameter = getParameterAsString("parameter_string");
	logMessage("Creating condition '"+className+"' with parameter '"+parameter+"'", LogService.MINIMUM);
	return new IOObject[] { 
	    new FilteredExampleSet(inputSet,
				   ConditionExampleReader.createCondition(className, inputSet,  parameter)) 
		};
    }

    public Class[] getInputClasses() {  return INPUT_CLASSES;  }
    public Class[] getOutputClasses() {  return OUTPUT_CLASSES;   }


    public List getParameterTypes() {
	List types = super.getParameterTypes();
	ParameterType type = new ParameterTypeStringCategory("condition_class", 
							     "Implementation of the condition.", 
							     ConditionExampleReader.KNOWN_CONDITION_IMPLEMENTATIONS, 
							     ConditionExampleReader.KNOWN_CONDITION_IMPLEMENTATIONS[0]);
	type.setExpert(false);
	types.add(type);
	type = new ParameterTypeString("parameter_string", "Parameter string for the condition, e.g. 'attribute=value' for the AttributeValueFilter.", true);
	type.setExpert(false);
	types.add(type);
	return types;
    }
}