obfuscator.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.example.ExampleSet;
import edu.udo.cs.yale.example.Attribute;
import edu.udo.cs.yale.tools.LogService;
import edu.udo.cs.yale.tools.RandomGenerator;

import java.util.List;
import java.util.Iterator;
import java.util.Map;
import java.util.HashMap;
import java.io.*;

/** This operator takes an <code>ExampleSet</code> as input and maps all nominal values
 *  to randomly created strings. The names and the construction descriptions of all attributes
 *  will also replaced by random strings. This operator can be used to anonymize your data.
 *  It is possible to save the obfuscating map into a file which can be used to remap the old 
 *  values and names. Please use the operator <code>Deobfuscator</code> for this purpose. 
 *  The new example set can be written with an <code>ExampleSetWriter</code>.
 *
 *  @version $Id: Obfuscator.java,v 1.3 2004/09/17 12:57:42 ingomierswa Exp $
 */
public class Obfuscator extends Operator {

    public IOObject[] apply() throws OperatorException {
	// init
	ExampleSet exampleSet = (ExampleSet)getInput(ExampleSet.class);
	Map obfuscatorMap = new HashMap();

	// obfuscate regular attributes
	for (int i = 0; i < exampleSet.getNumberOfAttributes(); i++) {
	    obfuscateAttribute(exampleSet.getAttribute(i), obfuscatorMap);
	}

	// obfuscate special attributes	
	Iterator i = exampleSet.getSpecialAttributeNames().iterator();
	while (i.hasNext()) {
	    obfuscateAttribute(exampleSet.getAttribute((String)i.next()), obfuscatorMap);
	}

	exampleSet.recalculateAllAttributeStatistics();
	
	String filename = getParameterAsString("obfuscation_map_file");
	if ((filename != null) && (filename.trim().length() > 0)) {
	    File file = getExperiment().resolveFileName(filename);
	    try {
		writeObfuscatorMap(obfuscatorMap, file);
	    } catch (IOException e) {
		throw new UserError(this, 303, filename, e.getMessage());
	    }
	}

        return new IOObject[] { exampleSet };
    }
    
    private void obfuscateAttribute(Attribute attribute, Map obfuscatorMap) {
	String oldName = attribute.getName();
	String newName = RandomGenerator.getGlobalRandomGenerator().nextString(8);
	attribute.setName(newName);
	attribute.clearConstructionDescription();
	obfuscatorMap.put(newName, oldName);
	
	if (attribute.isNominal()) {
	    Iterator v = attribute.getValues().iterator();
	    while (v.hasNext()) {
		String oldValue = (String)v.next();
		String newValue = RandomGenerator.getGlobalRandomGenerator().nextString(8);
		attribute.replaceValue(oldValue, newValue);
		obfuscatorMap.put(oldName + ":" + newValue, oldValue);
	    }
	}
    }

    private void writeObfuscatorMap(Map obfuscatorMap, File file) throws IOException {
	PrintWriter out = new PrintWriter(new FileWriter(file));
	Iterator i = obfuscatorMap.keySet().iterator();
	while (i.hasNext()) {
	    String key   = (String)i.next();
	    String value = (String)obfuscatorMap.get(key);
	    out.println(key + "\t" + value);
	}
	out.close();
    }

    public Class[] getInputClasses() {  return new Class[] { ExampleSet.class };  }
    public Class[] getOutputClasses() {  return new Class[] { ExampleSet.class };  }


    public List getParameterTypes() {
	List types = super.getParameterTypes();
	ParameterType type = new ParameterTypeFile("obfuscation_map_file", "File where the obfuscator map should be written to.", true);
	types.add(type);
	return types;
    }
}