001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.hadoop.tools.twitter.token.mode.pointwisemi.sort;
031
032import java.io.ByteArrayInputStream;
033import java.io.DataInputStream;
034import java.io.IOException;
035import org.apache.hadoop.io.BytesWritable;
036import org.apache.hadoop.io.RawComparator;
037
038
039/**
040 * Read a tokenpair and make sure the single words appear before the pair words
041 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
042 *
043 */
044public class PMISortValueGroupingComparator implements RawComparator<BytesWritable> {
045
046        @Override
047        public int compare(BytesWritable o1, BytesWritable o2) {
048                return compareData(o1.getBytes(),0,o1.getLength(),o2.getBytes(),0,o2.getLength());
049        }
050
051        @Override
052        public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
053                return compareData(b1,s1+4,l1-4,b2,s2+4,l2-4);
054        }
055
056        private int compareData(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
057                DataInputStream dis1 = new DataInputStream(new ByteArrayInputStream(b1,s1,l1));
058                DataInputStream dis2 = new DataInputStream(new ByteArrayInputStream(b2,s2,l2));
059                
060                try {
061                        // group up by times first
062                        long t1;
063                        long t2;
064                        t1 = dis1.readLong();
065                        t2 = dis2.readLong();
066                        
067                        if(t1 < t2){
068                                return -1;
069                        }
070                        else if(t1 > t2){
071                                return 1;
072                        }
073                        return 0;
074                } catch (IOException e) {
075                }
076                return 0;
077        }
078}