/**
* 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.classifier.bayes.mapreduce.common;
import java.io.IOException;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;
import org.apache.mahout.common.StringTuple;
/**
*
* Calculates weight sum for a unique label, and feature
*
*/
public class BayesWeightSummerMapper extends MapReduceBase implements
Mapper<StringTuple,DoubleWritable,StringTuple,DoubleWritable> {
/**
* We need to calculate the weight sums across each label and each feature
*
* @param key
* The label,feature tuple containing the tfidf value
*/
@Override
public void map(StringTuple key,
DoubleWritable value,
OutputCollector<StringTuple,DoubleWritable> output,
Reporter reporter) throws IOException {
String label = key.stringAt(1);
String feature = key.stringAt(2);
reporter.setStatus("Bayes Weight Summer Mapper: " + key);
StringTuple featureSum = new StringTuple(BayesConstants.FEATURE_SUM);
featureSum.add(feature);
output.collect(featureSum, value); // sum of weight for all labels for a
// feature Sigma_j
StringTuple labelSum = new StringTuple(BayesConstants.LABEL_SUM);
labelSum.add(label);
output.collect(labelSum, value); // sum of weight for all features for a
// label Sigma_k
StringTuple totalSum = new StringTuple(BayesConstants.TOTAL_SUM);
output.collect(totalSum, value); // sum of weight of all features for all
// label Sigma_kSigma_j
}
}