featuregenerationoperator.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.UserError;
import edu.udo.cs.yale.operator.parameter.*;
import edu.udo.cs.yale.operator.OperatorException;
import edu.udo.cs.yale.generator.GenerationException;
import edu.udo.cs.yale.tools.LogService;
import edu.udo.cs.yale.tools.ParameterService;
import edu.udo.cs.yale.tools.Ontology;
import edu.udo.cs.yale.example.Attribute;
import edu.udo.cs.yale.example.AttributeParser;
import edu.udo.cs.yale.example.ExampleSet;
import edu.udo.cs.yale.generator.*;

import java.io.File;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

/** This operator generates new user specified features.
 *  The new features are specified by their function names (prefix notation) and their 
 *  arguments using the names of existing features.<br/>
 *  Legal function names include +, -, *, /, norm, sin, cos, tan, atan, exp, log, min, max, floor, ceil, round, sqrt, abs, and pow. 
 *  Constant values can be defined by &quot;const[value]()&quot; where value is the desired value. Do not forget the empty round brackets.
 *  Example: <code>+(a1, *(a2, a3))</code> will calculate the sum of the attribute 
 *  <code>a1</code> and the product of the attributes <code>a2</code> and <code>a3</code>.
 *  <br/>
 *  Features are generated in the following order
 *  <ol>
 *    <li>Features specified by the file referenced by the parameter "filename" are generated</li>
 *    <li>Features specified by the parameter list "functions" are generated</li>
 *    <li>If "keep_all" is false, all of the old attributes are removed now</li>
 *  </ol>
 *
 *  @yale.xmlclass FeatureGeneration
 *  @see edu.udo.cs.yale.generator.FeatureGenerator
 *  @author simon, ingo
 *  @version $Id: FeatureGenerationOperator.java,v 1.3 2004/08/27 11:57:44 ingomierswa Exp $
 */
public class FeatureGenerationOperator extends Operator {

    private static final Class[] INPUT_CLASSES  = { ExampleSet.class };
    private static final Class[] OUTPUT_CLASSES = { ExampleSet.class };

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


    public IOObject[] apply() throws OperatorException {
	ExampleSet exampleSet = (ExampleSet)((ExampleSet)getInput().getInput(ExampleSet.class)).clone();
	boolean keepAll = getParameterAsBoolean("keep_all");

	String filename = getParameterAsString("filename");
	try {
	    AttributeParser parser = new AttributeParser(exampleSet.getExampleTable());
	    
	    if (filename != null) {
		parser.parseAll(new FileReader(getExperiment().resolveFileName(filename)));
	    }
	    
	    Iterator j = getParameterList("functions").iterator();
	    while (j.hasNext()) {
		Object[] nameFunctionPair = (Object[])j.next();
		Attribute attribute = parser.parse((String)nameFunctionPair[1]);
		attribute.setName((String)nameFunctionPair[0]);
	    }

	    if (!keepAll) { exampleSet.removeAllAttributes(); }
	    parser.generateAll(exampleSet);

  	} catch (java.io.IOException e) {
  	    throw new UserError(this, e, 302, new Object[] {filename, e.getMessage()});
  	}

	return new IOObject[] { exampleSet };
    }


    public List getParameterTypes() {
	List types = super.getParameterTypes();
	ParameterType type = new ParameterTypeFile("filename", "Create the attributes listed in this file (written by an AttributeSetWriter).", true);
	type.setExpert(false);
	types.add(type);
	type = new ParameterTypeList("functions", "List of functions to generate.", 
				     new ParameterTypeString("function", "Function and arguments to use for generation."));
	type.setExpert(false);
	types.add(type);
	types.add(new ParameterTypeBoolean("keep_all", "If set to true, all the original attributes are kept, otherwise they are removed from the example set.", false));
	return types;
    }

}