code: package edu.jhu.thrax.hadoop.features.annotation;
  
  import java.io.IOException;
  import java.util.HashSet;
  import java.util.Set;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.mapreduce.Job;
  import org.apache.hadoop.mapreduce.Mapper;
  import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
  import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
  import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
  import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
  
  import edu.jhu.thrax.hadoop.datatypes.Annotation;
  import edu.jhu.thrax.hadoop.datatypes.FeaturePair;
  import edu.jhu.thrax.hadoop.datatypes.RuleWritable;
  import edu.jhu.thrax.hadoop.jobs.DefaultValues;
  import edu.jhu.thrax.hadoop.jobs.ExtractionJob;
  import edu.jhu.thrax.hadoop.jobs.ThraxJob;
  
  public class AnnotationFeatureJob implements ThraxJob {
  
    public AnnotationFeatureJob() {}
  
    protected static HashSet<Class<? extends ThraxJob>> prereqs =
        new HashSet<Class<? extends ThraxJob>>();
  
    public Set<Class<? extends ThraxJob>> getPrerequisites() {
      prereqs.add(ExtractionJob.class);
      return prereqs;
    }
  
    public static void addPrerequisites(Iterable<Class<? extends ThraxJob>> cs) {
      if (cs != null)
        for (Class<? extends ThraxJob> c : cs)
          prereqs.add(c);
    }
  
    public static void addPrerequisite(Class<? extends ThraxJob> c) {
      prereqs.add(c);
    }
  
    public String getOutputSuffix() {
      return getName();
    }
  
    public Job getJob(Configuration conf) throws IOException {
      String name = getName();
      Job job = new Job(conf, name);
      job.setJarByClass(this.getClass());
  
      job.setMapperClass(Mapper.class);
      job.setPartitionerClass(RuleWritable.YieldPartitioner.class);
      job.setReducerClass(AnnotationReducer.class);
  
      job.setInputFormatClass(SequenceFileInputFormat.class);
      job.setMapOutputKeyClass(RuleWritable.class);
      job.setMapOutputValueClass(Annotation.class);
      job.setOutputKeyClass(RuleWritable.class);
      job.setOutputValueClass(FeaturePair.class);
      job.setOutputFormatClass(SequenceFileOutputFormat.class);
  
      int num_reducers = conf.getInt("thrax.reducers", conf.getInt("mapreduce.job.reduces", DefaultValues.DEFAULT_NUM_REDUCERS));
      job.setNumReduceTasks(num_reducers);
  
      FileInputFormat.setInputPaths(job, new Path(conf.get("thrax.work-dir") + "rules"));
      FileOutputFormat.setOutputPath(job, new Path(conf.get("thrax.work-dir") + "annotation"));
      return job;
    }
  
    @Override
    public String getName() {
      return "annotation";
    }
  }
  