Hadoop之MapReduce程序应用一
摘要:MapReduce程序处理专利数据集。
关键词:MapReduce程序 专利数据集
数据源:专利引用数据集cite75_99.txt。(该数据集可以从网址 http://www.nber.org/patents/下载)
问题描述:
读取专利引用数据集并对它进行倒排。对于每一个专利,找到那些引用它的专利并进行合并。top5输出结果如下:
1 3964859, 4647229
10000 4539112
100000 5031388
1000006 4714284
1000007 4766693
解决方案:
1 开发工具: VM10+Ubuntu12.04+hadoop1.1.2+eclipse
2 在eclipse中创建一个工程,并且在工程里添加一个java类。
程序清单如下:
package com.wangluqing;
import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.KeyValueTextInputFormat;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.TextOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
public class MyJob1 extends Configured implements Tool {
public static class MapClass extends MapReduceBase implements Mapper<Text,Text,Text,Text> {
@Override
public void map(Text key, Text value, OutputCollector<Text, Text> output,
Reporter reporter) throws IOException {
// TODO Auto-generated method stub
output.collect(value, key);
}
}
public static class Reduce extends MapReduceBase implements Reducer<Text,Text,Text,Text> {
@Override
public void reduce(Text key, Iterator<Text> values,
OutputCollector<Text, Text> output, Reporter reporter)
throws IOException {
// TODO Auto-generated method stub
String csv = "";
while(values.hasNext()) {
if(csv.length()>0)
csv += ",";
csv += values.next().toString();
}
output.collect(key, new Text(csv));
}
}
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
String[] arg={"hdfs://hadoop:9000/user/root/input/cite75_99.txt","hdfs://hadoop:9000/user/root/output"};
int res = ToolRunner.run(new Configuration(),new MyJob1(), arg);
System.exit(res);
}
public int run(String[] args) throws Exception {
// TODO Auto-generated method stub
Configuration conf = getConf();
JobConf job = new JobConf(conf, MyJob1.class);
Path in = new Path(args[0]);
Path out = new Path(args[1]);
FileInputFormat.setInputPaths(job, in);
FileOutputFormat.setOutputPath(job, out);
job.setJobName("MyJob");
job.setMapperClass(MapClass.class);
job.setReducerClass(Reduce.class);
job.setInputFormat(KeyValueTextInputFormat.class);
job.setOutputFormat(TextOutputFormat.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
job.set("key.value.separator.in.input.line", ",");
JobClient.runJob(job);
return 0;
}
}
运行Run on hadoop,在Ubuntu 下执行命令
hadoop fs -cat /usr/root/output/part-00000 | head
可以查看到经过MapReduce程序处理后的结果。
总结:
第一:可以采用装有Hadoop版本对应插件的Eclipse集成开发工具进行MapReduce程序开发。
第二:根据数据流和问题域设计和编写MapReduce程序。
Resource:
1 http://www.wangluqing.com/2014/03/hadoop-mapreduce-programapp1/
2 参考《Hadoop实战》第四章 MapReduce基础程序