Create Finding rating of each video in youtube data

Finding rating of each video in youtube data

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+import java.io.IOException;
+
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.conf.*;
+import org.apache.hadoop.io.*;
+import org.apache.hadoop.mapreduce.*;
+import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
+import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
+import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
+import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
+
+   public class Video_rating {
+
+    public static class Map extends Mapper<LongWritable, Text, Text,
+FloatWritable> {
+
+       private Text video_name = new Text();
+       private  FloatWritable rating = new FloatWritable();
+       public void map(LongWritable key, Text value, Context context )
+throws IOException, InterruptedException {
+           String line = value.toString();
+           String str[]=line.split("\t");
+
+          if(str.length > 7){
+                video_name.set(str[0]);
+                if(str[6].matches("\\d+.+")){ //this regular expression
+specifies that the string should contain only floating values
+                float f=Float.parseFloat(str[6]); //typecasting string to float
+                rating.set(f);
+                }
+          }
+
+      context.write(video_name, rating);
+      }
+
+    }
+
+    public static class Reduce extends Reducer<Text, FloatWritable,
+Text, FloatWritable> {
+
+       public void reduce(Text key, Iterable<FloatWritable> values,
+Context context)
+         throws IOException, InterruptedException {
+           float sum = 0;
+           int l=0;
+           for (FloatWritable val : values) {
+                   l+=1;  //counts number of values are there for that key
+               sum += val.get();
+           }
+           sum=sum/l;   //takes the average of the sum
+           context.write(key, new FloatWritable(sum));
+       }
+    }
+
+    public static void main(String[] args) throws Exception {
+       Configuration conf = new Configuration();
+
+           @SuppressWarnings("deprecation")
+                Job job = new Job(conf, "videorating");
+           job.setJarByClass(Video_rating.class);
+
+           job.setMapOutputKeyClass(Text.class);
+           job.setMapOutputValueClass(FloatWritable.class);
+      //job.setNumReduceTasks(0);
+       job.setOutputKeyClass(Text.class);
+       job.setOutputValueClass(FloatWritable.class);
+
+       job.setMapperClass(Map.class);
+       job.setReducerClass(Reduce.class);
+
+       job.setInputFormatClass(TextInputFormat.class);
+       job.setOutputFormatClass(TextOutputFormat.class);
+
+       FileInputFormat.addInputPath(job, new Path(args[0]));
+       FileOutputFormat.setOutputPath(job, new Path(args[1]));
+        Path out=new Path(args[1]);
+        out.getFileSystem(conf).delete(out);
+       job.waitForCompletion(true);
+    }
+
+  }