/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.mahout.math.hadoop.similarity;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.common.ClassUtils;
import org.apache.mahout.common.StringTuple;
import org.apache.mahout.common.distance.DistanceMeasure;
import org.apache.mahout.math.NamedVector;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
import java.io.IOException;
import java.util.List;
public final class VectorDistanceMapper
extends Mapper<WritableComparable<?>, VectorWritable, StringTuple, DoubleWritable> {
private DistanceMeasure measure;
private List<NamedVector> seedVectors;
@Override
protected void map(WritableComparable<?> key, VectorWritable value, Context context)
throws IOException, InterruptedException {
String keyName;
Vector valVec = value.get();
if (valVec instanceof NamedVector) {
keyName = ((NamedVector) valVec).getName();
} else {
keyName = key.toString();
}
for (NamedVector seedVector : seedVectors) {
double distance = measure.distance(seedVector, valVec);
StringTuple outKey = new StringTuple();
outKey.add(seedVector.getName());
outKey.add(keyName);
context.write(outKey, new DoubleWritable(distance));
}
}
@Override
protected void setup(Context context) throws IOException, InterruptedException {
super.setup(context);
Configuration conf = context.getConfiguration();
measure =
ClassUtils.instantiateAs(conf.get(VectorDistanceSimilarityJob.DISTANCE_MEASURE_KEY), DistanceMeasure.class);
measure.configure(conf);
seedVectors = SeedVectorUtil.loadSeedVectors(conf);
}
}