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.fastkmeans;
031
032import java.io.ByteArrayInputStream;
033import java.io.IOException;
034
035import org.apache.hadoop.io.BytesWritable;
036import org.apache.hadoop.io.IntWritable;
037import org.apache.hadoop.io.Text;
038import org.apache.hadoop.mapreduce.Mapper;
039import org.apache.hadoop.mapreduce.Reducer;
040import org.openimaj.tools.clusterquantiser.FileType;
041import org.openimaj.tools.clusterquantiser.Header;
042
043/**
044 * Map Reduce job to count features
045 * 
046 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
047 * 
048 */
049public class FeatureCount {
050        private static final String FILETYPE_KEY = "clusterquantiser.FileType";
051
052        /**
053         * Map class. Emits number of features per record.
054         * 
055         * @author Sina Samangooei (ss@ecs.soton.ac.uk)
056         * 
057         */
058        public static class Map extends Mapper<Text, BytesWritable, Text, IntWritable>
059        {
060                private final static IntWritable nfeatures = new IntWritable(1);
061                private Text word = new Text("total");
062                private static FileType fileType = null;
063
064                @Override
065                protected void setup(Mapper<Text, BytesWritable, Text, IntWritable>.Context context) throws IOException,
066                                InterruptedException
067                {
068                        if (fileType == null) {
069                                fileType = FileType.valueOf(context.getConfiguration().get(FILETYPE_KEY));
070                        }
071                }
072
073                @Override
074                public void map(Text key, BytesWritable value, Context context) throws IOException, InterruptedException {
075                        final Header input = fileType.readHeader(new ByteArrayInputStream(value.getBytes()));
076                        nfeatures.set(input.nfeatures);
077                        context.write(word, nfeatures);
078                }
079        }
080
081        /**
082         * Reduce class. Combines counts per map record into overall sum.
083         * 
084         * @author Sina Samangooei (ss@ecs.soton.ac.uk)
085         * 
086         */
087        public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> {
088                @Override
089                public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException,
090                                InterruptedException
091                {
092                        int sum = 0;
093                        for (final IntWritable val : values) {
094                                sum += val.get();
095                        }
096                        context.write(key, new IntWritable(sum));
097                }
098        }
099}