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UnitMultiplication.java
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UnitMultiplication.java
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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.chain.ChainMapper;
import org.apache.hadoop.mapreduce.lib.input.MultipleInputs;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class UnitMultiplication {
public static class TransitionMapper extends Mapper<Object, Text, Text, Text> {
@Override
public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
String line = value.toString().trim();
String[] fromTo = line.split("\t");
if(fromTo.length == 1 || fromTo[1].trim().equals("")) {
return;
}
String from = fromTo[0];
String[] tos = fromTo[1].split(",");
for (String to: tos) {
context.write(new Text(from), new Text(to + "=" + (double)1/tos.length));
}
}
}
public static class PRMapper extends Mapper<Object, Text, Text, Text> {
@Override
public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
String[] pr = value.toString().trim().split("\t");
context.write(new Text(pr[0]), new Text(pr[1]));
}
}
public static class MultiplicationReducer extends Reducer<Text, Text, Text, Text> {
float beta;
@Override
public void setup(Context context) {
Configuration conf = context.getConfiguration();
beta = conf.getFloat("beta", 0.2f);
}
@Override
public void reduce(Text key, Iterable<Text> values, Context context)
throws IOException, InterruptedException {
List<String> transitionUnit = new ArrayList<String>();
double prUnit = 0;
for (Text value: values) {
if(value.toString().contains("=")) {
transitionUnit.add(value.toString());
}
else {
prUnit = Double.parseDouble(value.toString());
}
}
for (String unit: transitionUnit) {
String outputKey = unit.split("=")[0];
double relation = Double.parseDouble(unit.split("=")[1]);
//transition matrix * pageRank matrix * (1-beta)
String outputValue = String.valueOf(relation * prUnit * (1-beta));
context.write(new Text(outputKey), new Text(outputValue));
}
}
}
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
conf.setFloat("beta", Float.parseFloat(args[3]));
Job job = Job.getInstance(conf);
job.setJarByClass(UnitMultiplication.class);
ChainMapper.addMapper(job, TransitionMapper.class, Object.class, Text.class, Text.class, Text.class, conf);
ChainMapper.addMapper(job, PRMapper.class, Object.class, Text.class, Text.class, Text.class, conf);
job.setReducerClass(MultiplicationReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
MultipleInputs.addInputPath(job, new Path(args[0]), TextInputFormat.class, TransitionMapper.class);
MultipleInputs.addInputPath(job, new Path(args[1]), TextInputFormat.class, PRMapper.class);
FileOutputFormat.setOutputPath(job, new Path(args[2]));
job.waitForCompletion(true);
}
}