Scala实现Mapreduce程序4-----数据去重

数据去重，key只输出一次

scala实现：先groupByKey(),然后SortByKey(),然后输出keys

object Reduplicate {  def main(args: Array[String]): Unit = {    val conf=new SparkConf().setMaster("local").setAppName("remove duplication");    val sc=new SparkContext(conf);    val line=sc.textFile("");    line.filter(_.trim.length>0).map(line=>(line.trim,"")).groupByKey().sortByKey().keys.collect()

}

}

MapReduce实现：以整个数据作为key，reduce过程中输出key就可以了

package HadoopvsSpark;

import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Job;import org.apache.hadoop.mapreduce.Mapper;import org.apache.hadoop.mapreduce.Reducer;import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;import org.apache.hadoop.util.GenericOptionsParser;import java.io.IOException;

//对数据进行去重，以整个数据作为key，reduce过程中输出key就可以了

/** * Created by Administrator on 2017/5/25. */public class Duplicate {    public static class Map extends Mapper<Object,Text,Text,Text>{

private static Text text=new Text(  );        public void map(Object key,Text value,Context context) throws IOException, InterruptedException {            text=value;            context.write( new Text(text),new Text(" ") );        }    }

public static class Reduce extends Reducer<Text,Text,Text,Text>{        public void reduce(Text key,Iterable<Text> values,Context context) throws IOException, InterruptedException {            context.write( key,new Text( "" ) );        }    }

public static void  main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {        Job job=new Job();        Configuration conf=new Configuration();        conf.set("mapred.job.tracker","192.169.1.101:8200");

String[] input=new String[]{"a","s"};        String[] otherArgs=new GenericOptionsParser(conf,input).getRemainingArgs();        if(otherArgs.length!=2){            System.err.println("Usage: Data Deduplication <in> <out>");            System.exit(2);        }

job.setJarByClass(Duplicate.class);        FileInputFormat.addInputPath( job,new Path( otherArgs[0] ) );        FileOutputFormat.setOutputPath( job,new Path(otherArgs[1]) );

job.setOutputKeyClass( Text.class);        job.setOutputValueClass( Text.class );        job.setMapperClass( Map.class );        job.setCombinerClass( Reduce.class );        job.setReducerClass( Reduce.class);        System.out.println(job.waitForCompletion( true )? 1:0 );     }

}