SentenceShuffler.java

/**
 * CrowdTransEval, a toolkit for evaluating machine translation
 * system by using crowdsourcing.
 * Copyright (C) 2012 Alejandro Navarro Fulleda <anf5@alu.ua.es>
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */
package es.ua.alex952.cf_helpers;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.Random;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Shuffler class for creating new sentences from another
 *
 * @author alex952
 */
public class SentenceShuffler {

	private int degree;
	private Random r;

	/**
	 * Constructor of the class with the degree of shuffling
	 * 
	 * @param degree degree of shuffling
	 * @throws Exception 
	 */
	public SentenceShuffler(int degree) throws Exception {
		if(degree < 1 || degree > 5)
			throw new Exception("The degree of shuffling must be an integer between 1 and 5");
		
		this.degree = degree;
	}

	/**
	 * Shuffles a sentence with the algorithm implemented
	 * 
	 * @param sentenceOrig sentece to be shuffled
	 * @return the sentece already shuffled
	 */
	public String shuffle(String sentenceOrig) {
		String sentence = sentenceOrig.toLowerCase();
		
		r = new Random((new Date()).getTime());
		
		String[] nwords = sentence.split("\\s+");
		
		int blocks = (int) Math.floor(nwords.length/15.0);
		if (blocks == 0)
			blocks = 1;
		
		ArrayList<String> words = new ArrayList<String>();
		
		for (int i = 0; i < nwords.length; i++) {
			int index = 0;
			String sblock = "";
			
			while (index < blocks && i < nwords.length) {
				sblock += nwords[i];
				index++;
				
				if (index != blocks) {
					sblock += " ";
					i++;
				}
			}
			
			words.add(sblock);
		}
		
		ArrayList<Integer> positions = new ArrayList<Integer>();
		for (int i = 0; i < words.size(); i++) {
			positions.add(i);
		}
		
		int count = this.degree;
		int length = words.size();
		
		while (count > 0) {
			
			boolean cont = count*2 < positions.size();
			if (!cont)
				break;
			
			int from = r.nextInt(positions.size());
			int to = r.nextInt(positions.size());
                        while (to == from)
                            to = r.nextInt(positions.size());
			
			Collections.swap(words, positions.get(from), positions.get(to));
			
			int max = Math.max(from, to);
                        positions.remove(max);
                        
                        if (from != to) {
                            int min = Math.min(from, to);
                            positions.remove(min);
                        }
			count--;
		}
		
		String ret = "";
		
		for (int i = 0; i < words.size(); i++) {
			ret += words.get(i);
			
			if (i < words.size() - 1) {
				ret += " ";
			}
		}
		
		ret = Character.toUpperCase(ret.charAt(0)) + ret.substring(1, ret.length());
		
		return ret;
	}
}