mapred找共同朋友，数据格式如下：
A B C D E F
B A C D E
C A B E
D A B E
E A B C D
F A
第一字母表示本人，其他是他的朋友，找出有共同朋友的人，和共同朋友是谁
答案如下：
A B C D E F
B A C D E
C A B E
D A B E
E A B C D
F A
第一字母表示本人，其他是他的朋友，找出有共同朋友的人，和共同朋友是谁
答案如下：
-
package wzx.mr3;
import java.io.IOException;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.TreeSet;
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.Mapper.Context;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
public class FindFriend {
public static class ChangeMapper extends Mapper
@Override
public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
StringTokenizer itr = new StringTokenizer(value.toString());
Text owner = new Text();
Setset = new TreeSet ();
owner.set(itr.nextToken());
while (itr.hasMoreTokens()) {
set.add(itr.nextToken());
}
String[] friends = new String[set.size()];
friends = set.toArray(friends);
for(int i=0;i
System.out.println(new Text(outputkey)+"----"+owner);
context.write(new Text(outputkey),owner);
}
}
}
}
public static class FindReducer extends Reducer
public void reduce(Text key, Iterablevalues,
Context context) throws IOException, InterruptedException {
String commonfriends ="";
for (Text val : values) {
if(commonfriends == ""){
commonfriends = val.toString();
}else{
commonfriends = commonfriends+":"+val.toString();
}
}
context.write(key, new Text(commonfriends));
}
}
public static void main(String[] args) throws IOException,
InterruptedException, ClassNotFoundException {
Configuration conf = new Configuration();
args = new String[2];
args[0] = "hdfs://192.168.0.237:9000/usr/wzx/input2/cs1.txt";
args[1] = "hdfs://192.168.0.237:9000/usr/wzx/output2";
Job job = new Job(conf, "word count");
job.setJarByClass(FindFriend.class);
job.setMapperClass(ChangeMapper.class);
job.setCombinerClass(FindReducer.class);
job.setReducerClass(FindReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
for (int i = 0; i < args.length - 1; ++i) {
FileInputFormat.addInputPath(job, new Path(args[i]));
}
FileOutputFormat.setOutputPath(job,
new Path(args[args.length - 1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/29754888/viewspace-1445561/ ，如需转载，请注明出处，否则将追究法律责任。
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