content: package com.manning.hip.ch3.avro;
  
  import com.manning.hip.ch5.SmallFilesMapReduce;
  import com.manning.hip.ch3.avro.gen.Stock;
  import com.manning.hip.ch3.avro.gen.StockAvg;
  import org.apache.avro.mapred.AvroInputFormat;
  import org.apache.avro.mapred.AvroJob;
  import org.apache.avro.mapred.AvroOutputFormat;
  import org.apache.avro.mapred.AvroWrapper;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.io.DoubleWritable;
  import org.apache.hadoop.io.NullWritable;
  import org.apache.hadoop.io.Text;
  import org.apache.hadoop.io.compress.SnappyCodec;
  import org.apache.hadoop.mapred.*;
  
  import java.io.IOException;
  import java.util.Iterator;
  
  public class AvroStockMapReduce {
  
    public static void main(String... args) throws Exception {
      JobConf job = new JobConf();
      job.setJarByClass(SmallFilesMapReduce.class);
      Path input = new Path(args[0]);
      Path output = new Path(args[1]);
  
      output.getFileSystem(job).delete(output, true);
  
      job.set(AvroJob.INPUT_SCHEMA, Stock.SCHEMA$.toString());
      job.set(AvroJob.OUTPUT_SCHEMA, StockAvg.SCHEMA$.toString());
      job.set(AvroJob.OUTPUT_CODEC, SnappyCodec.class.getName());
  
      job.setInputFormat(AvroInputFormat.class);
      job.setOutputFormat(AvroOutputFormat.class);
  
      job.setMapperClass(Map.class);
      job.setReducerClass(Reduce.class);
  
      job.setMapOutputKeyClass(Text.class);
      job.setMapOutputValueClass(DoubleWritable.class);
  
      job.setOutputKeyClass(Text.class);
      job.setOutputValueClass(DoubleWritable.class);
  
      FileInputFormat.setInputPaths(job, input);
      FileOutputFormat.setOutputPath(job, output);
  
      JobClient.runJob(job);
    }
  
    public static class Map
        implements
        Mapper<AvroWrapper<Stock>, NullWritable, Text, DoubleWritable> {
  
      public void map(AvroWrapper<Stock> key,
                      NullWritable value,
                      OutputCollector<Text, DoubleWritable> output,
                      Reporter reporter) throws IOException {
        output.collect(new Text(key.datum().getSymbol().toString()),
            new DoubleWritable(key.datum().getOpen()));
      }
  
      public void close() throws IOException {
      }
  
      public void configure(JobConf job) {
      }
    }
  
    public static class Reduce
        implements Reducer<Text, DoubleWritable, AvroWrapper<StockAvg>,
        NullWritable> {
  
      public void reduce(Text key,
                         Iterator<DoubleWritable> values,
                         OutputCollector<AvroWrapper<StockAvg>,
                             NullWritable> output,
                         Reporter reporter) throws IOException {
        double total = 0.0;
        double count = 0;
        while (values.hasNext()) {
          total += values.next().get();
          count++;
        }
        StockAvg avg = new StockAvg();
        avg.setSymbol(key.toString());
        avg.setAvg(total / count);
        output.collect(new AvroWrapper<StockAvg>(avg),
            NullWritable.get());
      }
  
      public void close() throws IOException {
      }
  
      public void configure(JobConf job) {
      }
    }
  }
  