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MovieAverage.java
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MovieAverage.java
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import java.io.IOException;
import java.util.StringTokenizer;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.FloatWritable;
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;
public class MovieAverage
{
public static class TokenizerMapper extends Mapper<Object, Text, Text, FloatWritable>
{
private Text movie_name = new Text();
public void map(Object key, Text value, Context context) throws IOException, InterruptedException
{
for (String movie : value.toString().split("\n") ) {
String[] splitted = movie.split(";");
//IntWritable rating = new IntWritable(Integer.parseInt(splitted[1]));
FloatWritable rating = new FloatWritable(Float.parseFloat(splitted[1]));
movie_name.set(splitted[0]);
context.write(movie_name, rating);
}
}
}
public static class IntSumReducer extends Reducer<Text, FloatWritable, Text, FloatWritable>
{
private FloatWritable result = new FloatWritable();
public void reduce(Text key, Iterable<FloatWritable> values, Context context) throws IOException, InterruptedException
{
float sum = 0, num = 0;
for (FloatWritable val : values) {
sum += val.get();
num += 1;
}
float avg = sum / num;
result.set(avg);
context.write(key, result);
}
}
public static void main(String[] args) throws Exception
{
Configuration conf = new Configuration();
String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
if (otherArgs.length != 2)
{
System.err.println("Usage: movieaverage <in> <out>");
System.exit(2);
}
Job job = new Job(conf, "movie average");
job.setJarByClass(MovieAverage.class);
job.setMapperClass(TokenizerMapper.class);
job.setCombinerClass(IntSumReducer.class);
job.setReducerClass(IntSumReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(FloatWritable.class);
FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}