我试图在Mapreduce中实现简单的组。下面Reducer类在Hadoop中没有按预期工作MapReduce
我输入文件中给出:
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
我的映射类:
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));
}
}
减速机类:
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);
}
}
驱动程序类:
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);
}
}
预期的输出应该是:
10 8750
20 10875
30 9400
但它打印如下输出。它没有汇总这些值。 它像身份缩减器一样工作。
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
减速机功能不能正常工作。