attributevaluemapper.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 java.util.List;

/** This operator takes an <code>ExampleSet</code> as input and maps the values
 *  of certain attributes to other values. For example, it can replace all occurrences
 *  of the String "unknown" in a nominal Attribute by a default String, for all
 *  examples in the ExampleSet.
 *
 *  @version $Id: AttributeValueMapper.java,v 1.8 2004/09/17 16:03:10 ingomierswa Exp $
 */
public class AttributeValueMapper extends Operator {

    public IOObject[] apply() throws OperatorException {
	// init
	ExampleSet inputSet = (ExampleSet)getInput(ExampleSet.class);
	String attributeName = getParameterAsString("attribute_name");
        String replaceWhat = getParameterAsString("replace_what");
        String replaceBy = getParameterAsString("replace_by");
	Attribute attribute = inputSet.getAttribute(attributeName);
	
	// some checks
	if (attribute == null) {
	    throw new UserError(this, 111, attributeName);
        }

	if (!attribute.isNominal()) {
	    throw new UserError(this, 103, "attribute value mapping", attribute);
	}
	
	// the replacement
	attribute.replaceValue(replaceWhat, replaceBy);

	inputSet.recalculateAttributeStatistics(attribute);
	
        return new IOObject[] { inputSet };
    }


    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 ParameterTypeString("attribute_name", "Mapping of values will be applied to this attribute.", false);
	types.add(type);
	type = new ParameterTypeString("replace_what", 
				       "All occurrences of this value will be replaced.",
				       false);
	types.add(type);
	type = new ParameterTypeString("replace_by", 
				       "The new attribute value to use.", 
				       false);
	types.add(type);
	return types;
    }
}