我試圖在Mapreduce中實現簡單的組。下面Reducer類在Hadoop中沒有按預期工作MapReduce
我輸入文件中給出:
7369,SMITH,CLERK,800,20
7499,ALLEN,SALESMAN,1600,30
7521,WARD,SALESMAN,1250,30
7566,JONES,MANAGER,2975,20
7654,MARTIN,SALESMAN,1250,30
7698,BLAKE,MANAGER,2850,30
7782,CLARK,MANAGER,2450,10
7788,SCOTT,ANALYST,3000,20
7839,KING,PRESIDENT,5000,10
7844,TURNER,SALESMAN,1500,30
7876,ADAMS,CLERK,1100,20
7900,JAMES,CLERK,950,30
7902,FORD,ANALYST,3000,20
7934,MILLER,CLERK,1300,10
我的映射類:
public class Groupmapper extends Mapper<Object,Text,IntWritable,IntWritable> {
@Override
public void map(Object key, Text value, Context context) throws IOException, InterruptedException{
String line = value.toString();
String[] parts=line.split(",");
String token1=parts[3];
String token2=parts[4];
int deptno=Integer.parseInt(token2);
int sal=Integer.parseInt(token1);
context.write(new IntWritable(deptno),new IntWritable(sal));
}
}
減速機類:
public class Groupreducer extends Reducer<IntWritable, IntWritable, IntWritable, IntWritable> {
IntWritable result=new IntWritable();
public void Reduce(IntWritable key,Iterable<IntWritable> values, Context context) throws IOException, InterruptedException{
int sum=0;
for(IntWritable val:values){
sum+=val.get();
}
result.set(sum);
context.write(key,result);
}
}
驅動程序類:
public class Group {
public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException {
Configuration conf=new Configuration();
Job job=Job.getInstance(conf,"Group");
job.setJarByClass(Group.class);
job.setMapperClass(Groupmapper.class);
job.setCombinerClass(Groupreducer.class);
job.setReducerClass(Groupreducer.class);
job.setOutputKeyClass(IntWritable.class);
job.setOutputValueClass(IntWritable.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}
預期的輸出應該是:
10 8750
20 10875
30 9400
但它打印如下輸出。它沒有彙總這些值。 它像身份縮減器一樣工作。
10 1300
10 5000
10 2450
20 1100
20 3000
20 800
20 2975
20 3000
30 1500
30 1600
30 2850
30 1250
30 1250
30 950
減速機功能不能正常工作。