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.IOException;
033import java.util.Map;
034
035import org.apache.hadoop.fs.Path;
036import org.apache.hadoop.io.BytesWritable;
037import org.apache.hadoop.mapreduce.Mapper;
038import org.openimaj.hadoop.tools.twitter.token.mode.pointwisemi.count.PairMutualInformation;
039import org.openimaj.hadoop.tools.twitter.token.mode.pointwisemi.count.TokenPairCount;
040import org.openimaj.hadoop.tools.twitter.token.mode.pointwisemi.count.TokenPairUnaryCount;
041import org.openimaj.io.IOUtils;
042
043/**
044 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
045 *
046 */
047public class PMISortMapper extends Mapper<BytesWritable, BytesWritable, BytesWritable, BytesWritable> {
048        private static double minp = -1;
049        private static int minPairCount;
050        private static Path pairmiloc;
051        private static Map<Long, Long> timecounts;
052        /**
053         * does nothing
054         */
055        public PMISortMapper(){
056                
057        }
058        
059        @Override
060        public void setup(Mapper<BytesWritable, BytesWritable,BytesWritable,BytesWritable>.Context context) throws IOException ,InterruptedException {
061                load(context);
062        };
063        private synchronized static void load(Mapper<BytesWritable, BytesWritable,BytesWritable,BytesWritable>.Context context) throws IOException {
064                if(timecounts==null){                   
065                        minp = context.getConfiguration().getFloat(PMIPairSort.MINP_KEY, -1);
066                        minPairCount = context.getConfiguration().getInt(PMIPairSort.MINPAIRCOUNT_KEY, 0);
067                        pairmiloc = new Path(context.getConfiguration().get(PMIPairSort.PAIRMI_LOC));
068                        timecounts = PairMutualInformation.loadTimeCounts(pairmiloc);
069                }
070        }
071
072        @Override
073        public void map(BytesWritable key, BytesWritable value, Mapper<BytesWritable, BytesWritable,BytesWritable,BytesWritable>.Context context) throws IOException ,InterruptedException {
074                TokenPairUnaryCount tpuc = IOUtils.deserialize(value.getBytes(), TokenPairUnaryCount.class);
075                long timet = TokenPairCount.timeFromBinaryIdentity(key.getBytes());
076                long n = timecounts.get(timet);
077                if( minPairCount != -1 && tpuc.paircount < minPairCount ) return;
078                double pmi = tpuc.pmi(n);
079                if(new Double(pmi).equals(Double.NaN)) return;
080                if( minp == -1 || pmi > minp){
081                        byte[] serialized = PMIPairSort.timePMIBinary(timet,pmi);
082                        context.write(new BytesWritable(serialized), value);
083                }
084        };
085}