SumRDFReducer.java

package com.ontology2.bakemono.sumRDF;

import org.apache.hadoop.io.FloatWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;

//
// This code is copied almost verbatim from the SumUsageReducer defined in the
// telepath project.  It would be nice to get both of these sharing the same
// reducer
//

public class SumRDFReducer extends Reducer<Text,FloatWritable,Text,Text> {
    private static final String THIS="com.ontology2.telepath.sumUsage";
    public static final String PREDICATE=THIS+".predicate";
    final String predicate="<http://rdf.basekb.com/public/subjectiveEye3D>";

//    @Override
//    protected void setup(Context context) throws IOException, InterruptedException {
//        predicate=context.getConfiguration().get(PREDICATE);
//    }

    @Override
    protected void reduce(Text key, Iterable<FloatWritable> values, Context context) throws IOException, InterruptedException {
        float sum=0.0F;
        for(FloatWritable value:values)
            sum += value.get();

        StringBuffer remainder=new StringBuffer(predicate);
        remainder.append("\t\"");
        remainder.append(sum);
        remainder.append("\"^^<http://www.w3.org/2001/XMLSchema#float>\t.");
        context.write(
                key,
                new Text(remainder.toString())
        );
    }
}