exampleformatter.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 java.util.List;
import java.util.LinkedList;

/** Formats an example as specified by the format string.
 *  The dollar sign '$' is an escape character. Squared brackets '[' and ']' 
 *  have a special meaning. The following escape sequences are
 *  interpreted:
 *  <dl>
 *    <dt>$a[separator]:</dt><dd> All attributes separated by separator</dd>
 *    <dt>$s[separator][indexSeparator]:</dt><dd> Sparse format. For all non 0 
 *           attributes the following strings are concatenated: 
 *           the column index, the value of indexSeparator, the attribute value. Attributes
 *           are separated by separator.</dd>
 *    <dt>$v[name]:</dt><dd> The value of the named attribute (both regular and special attributes)</dd>
 *    <dt>$c[index]:</dt><dd> The value of the attribute with the given index in the example set</dd>
 *    <dt>$l:</dt><dd> The label</dd>
 *    <dt>$p:</dt><dd> The predicted label</dd> 
 *    <dt>$i:</dt><dd> The id</dd>
 *    <dt>$w:</dt><dd> The weight</dd>
 *    <dt>$n:</dt><dd> The newline character</dd>
 *    <dt>$t:</dt><dd> The tabulator character</dd>
 *    <dt>$$:</dt><dd> The dollar sign</dd>
 *    <dt>$[:</dt><dd> The '[' character</dd>
 *    <dt>$]:</dt><dd> The ']' character</dd>
 *  </dl> 
 *
 *  @version $Id: ExampleFormatter.java,v 2.6 2004/09/17 12:57:38 ingomierswa Exp $
 */
public class ExampleFormatter {

    /** Represents one piece of formatting. */
    public static interface FormatCommand {
	public String format(Example example);
    }

    public static class SimpleCommand implements FormatCommand {
	private char command; 
	private String[] arguments;
	private SimpleCommand(char command, String[] arguments) {
	    this.command = command;
	    if ((command != 'a') &&
		(command != 's') &&
		(command != 'l') &&
		(command != 'p') &&
		(command != 'i') &&
		(command != 'w'))
		throw new IllegalArgumentException("Unknown command: '"+command+"'");
	    switch (command) {
	    case 'a': 
		if (arguments.length == 0) arguments = new String[] { Example.SEPARATOR };
		break;
	    case 's':
		if (arguments.length == 0) 
		    arguments = new String[] { Example.SEPARATOR, Example.SPARSE_SEPARATOR };
		if (arguments.length == 1)
		    arguments = new String[] { arguments[0], Example.SPARSE_SEPARATOR };
		break;
	    }
	    this.arguments = arguments;
	}
	public String format(Example example) {
	    switch (command) {
	    case 'a': return example.getAttributesAsString(arguments[0]);
	    case 's': return example.getAttributesAsSparseString(arguments[0], arguments[1]);
	    case 'l': return example.getLabelAsString();
	    case 'p': return example.getPredictedLabelAsString();
	    case 'i': return example.getId()+"";
	    case 'w': return example.getWeight()+"";
	    default: return command+"";
	    }
	}
    }

    public static class ValueCommand implements FormatCommand {
	private Attribute attribute;
	public ValueCommand(char command, String[] arguments, ExampleSet exampleSet) {
	    if (arguments.length < 1) 
		throw new IllegalArgumentException("Command 'v' needs argument!");
	    switch (command) {
		case 'v':
		    attribute = exampleSet.getAttribute(arguments[0]);
		    if (attribute == null)
			throw new IllegalArgumentException("Unknown attribute: '"+arguments[0]+"'!");
		    break;
		case 'c':
		    try {
			attribute = exampleSet.getAttribute(Integer.parseInt(arguments[0]));
		    } catch (NumberFormatException e) {
			throw new IllegalArgumentException("Argument for 'c' must be an integer!");
		    } catch (Throwable e) {
			throw new IllegalArgumentException("Illegal column: '"+arguments[0]+"'!");
		    }
		    break;
		default: throw new IllegalArgumentException("Illegal command for ValueCommand: '"+command+"'");
	    }
	}
	public String format(Example example) {
	    return example.getValueAsString(attribute);
	}
    }

    public static class TextCommand implements FormatCommand {
	private String text;
	private TextCommand(String text) { this.text = text; }
	public String format(Example example) { return text; }
    }

    /** The commands used subsequently to format the example. */
    private FormatCommand[] formatCommands;

    /** Constructs a new ExampleFormatter that executes the given array
     *  of formatting commands. The preferred way of creating an instance
     *  of ExampleFormatter is to {@link ExampleFormatter#compile(String, ExampleSet)} 
     *  a format string. */
    public ExampleFormatter(FormatCommand[] formatCommands) {
	this.formatCommands = formatCommands;
    }

    /** Factory method that compiles a format string and creates an
     *  instance of ExampleFormatter. */
    public static ExampleFormatter compile(String formatString, ExampleSet exampleSet) {
	List commandList = new LinkedList();
	compile(formatString, exampleSet, commandList);
	FormatCommand[] commands = new FormatCommand[commandList.size()];
	commandList.toArray(commands);
	return new ExampleFormatter(commands);
    }

    /** Adds all commands to the <code>commandList</code>. */
    private static void compile(String formatString, ExampleSet exampleSet, List commandList) {
	int start = 0;
	while (true) {
	    int tagStart = formatString.indexOf("$", start);
	    if (tagStart == -1) {
		commandList.add(new TextCommand(formatString.substring(start)));
		break;
	    }
	    
	    if (tagStart == formatString.length()-1) 
		throw new IllegalArgumentException("Format string ends in '$'.");

	    commandList.add(new TextCommand(formatString.substring(start, tagStart)));

	    char command = formatString.charAt(tagStart+1);
	    if ((command == '$') || (command == '[') || (command == ']')) {
		commandList.add(new TextCommand(""+command));
		start = tagStart+2;
		continue;
	    } else if (command == 'n') {
		commandList.add(new TextCommand("\n"));
		start = tagStart+2;
		continue;
	    } else if (command == 't') {
		commandList.add(new TextCommand("\t"));
		start = tagStart+2;
		continue;
	    }
	    
	    start = tagStart+2;
	    List argumentList = new LinkedList();
	    while ((start < formatString.length()) && 
		   (formatString.charAt(start) == '[')) {
		int end = formatString.indexOf(']', start);
		if (end == -1) throw new IllegalArgumentException("Unclosed '['!");
		argumentList.add(formatString.substring(start+1, end));
		start = end+1;
	    }
	    
	    String[] arguments = new String[argumentList.size()];
	    argumentList.toArray(arguments);
	    switch (command) {
	    case 'v':
	    case 'c':
		commandList.add(new ValueCommand(command, arguments, exampleSet));
		break;
	    default:
		commandList.add(new SimpleCommand(command, arguments));
		break;
	    }
	}
    }

    /** Formats a single example. */
    public String format(Example example) {
	StringBuffer str = new StringBuffer();
	for (int i = 0; i < formatCommands.length; i++) {
	    str.append(formatCommands[i].format(example));
	}
	return str.toString();
    }
}