databaseexampletable.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.example;

import edu.udo.cs.yale.tools.DatabaseHandler;

import java.util.List;
import java.sql.ResultSet;
import java.sql.SQLException;

public class DatabaseExampleTable extends ExampleTable {

    private DatabaseHandler databaseHandler;
    private String tableName;
    private int numOfColumns;
    private int size;

    private DatabaseExampleTable(List attributes, 
				 DatabaseHandler databaseHandler,
				 ResultSet resultSet,
				 String tableName, 
				 int numOfColumns) throws SQLException {
	super(attributes);

	this.databaseHandler = databaseHandler;
	this.tableName       = tableName;
	this.numOfColumns    = numOfColumns;
	this.size            = 0;

	//ResultSet resultSet = databaseHandler.query("select * from " + tableName);
	int numberOfAttributes = attributes.size();
	double[] minimum = new double[numberOfAttributes];
	double[] maximum = new double[numberOfAttributes];
	double[] average = new double[numberOfAttributes];
	for (int n = 0; n < numberOfAttributes; n++) {
	    minimum[n] = Double.POSITIVE_INFINITY;
	    maximum[n] = Double.NEGATIVE_INFINITY;
	    average[n] = 0.0d;
	}
	
	while (resultSet.next()) {
	    for (int n = 0; n < numberOfAttributes; n++) {
		Attribute attribute = (Attribute)attributes.get(n);
		double value = DatabaseDataRow.readColumn(resultSet, attribute);
		if (!Double.isNaN(value)) {
		    if (minimum[n] > value) minimum[n] = value;
		    if (maximum[n] < value) maximum[n] = value;
		    average[n] += value;
		}
	    }
	    size++;
	}

	for (int n = 0; n < numberOfAttributes; n++) {
	    average[n] /= (double)size;
	    Attribute attribute = (Attribute)attributes.get(n);
	    attribute.setMinimum(minimum[n]);
	    attribute.setMaximum(maximum[n]);
	    attribute.setAverage(average[n]);
	}
	//resultSet.close();
    }

    public static DatabaseExampleTable createDatabaseExampleTable(DatabaseHandler databaseHandler, String tableName) throws SQLException {
	ResultSet resultSet = databaseHandler.query("select * from " + tableName);
	List attributes = DatabaseHandler.createAttributes(resultSet);
	DatabaseExampleTable table = new DatabaseExampleTable(attributes,
							      databaseHandler, resultSet,
							      tableName, 
							      resultSet.getMetaData().getColumnCount());
	resultSet.close();
	return table;
    }

    public DataRowReader getDataReader() {
	try {
	    String query = "SELECT ";
	    boolean first = true;
	    for (int i = 0; i < getNumberOfAttributes(); i++) {
		Attribute a = getAttribute(i);
		if (a != null) {
		    if (!first) query += ", ";
		    first = false;
		    query += "\""+DatabaseHandler.getDatabaseName(a)+"\"";
		}		
	    }
	    query += " from "+tableName;
	    return new DatabaseDataRowReader(getAttributes(), databaseHandler.query(query));
	} catch (SQLException e) {
	    throw new RuntimeException("Error while creating database datarowreader: "+e, e);
	}
    }

    public int addAttribute(Attribute attribute) {
	int index = super.addAttribute(attribute);
	if (databaseHandler == null)
	    return index;
	try {
	    databaseHandler.addColumn(attribute, tableName);
	} catch (SQLException e) {
	    throw new RuntimeException("Error while adding a column to database: " + e, e);
	}
	return index;
    }

    public void removeAttribute(Attribute attribute) {
	super.removeAttribute(attribute);
	try {
	    databaseHandler.removeColumn(attribute, tableName);
	} catch (SQLException e) {
	    throw new RuntimeException("Error while removing a column from database: " + e, e);
	}
    }

    public int getSize() {
	return size;
    }
}