groupby

public static class Map extends Mapper<LongWritable, Text, Text, DoubleWritable> {
        //private final static DoubleWritable one = new DoubleWritable(1);
        private final static String emptyWords[] = { "" };

        @Override
        public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
            // TODO: à compléter
            String line = value.toString();
            // Une méthode pour créer des messages de log
//          LOG.info("MESSAGE INFO");

            String[] words = line.split(",");
            // La ligne est vide : on s'arrête
            if (Arrays.equals(words, emptyWords))
                return;

            //for (String word : words)
            try{
                context.write(new Text(words[5]), new DoubleWritable(Double.parseDouble(words[words.length-1])));
            }catch(RuntimeException e)
            {
                System.out.println(e);
            }

        }

    }

    public static class Reduce extends Reducer<Text, DoubleWritable, Text, DoubleWritable> {

        @Override
        public void reduce(Text key, Iterable<DoubleWritable> values, Context context)
                throws IOException, InterruptedException {
            // TODO: à compléter
            int sum = 0;

            for (DoubleWritable val : values)
                sum += val.get();

            context.write(key, new DoubleWritable(sum));
        }
    }