/**
* 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.vectorizer.term;
import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
/**
* TextVectorizer Document Frequency Count Mapper. Outputs 1 for each feature
*/
public class TermDocumentCountMapper extends Mapper<WritableComparable<?>, VectorWritable, IntWritable, LongWritable> {
private static final LongWritable ONE = new LongWritable(1);
private static final IntWritable TOTAL_COUNT = new IntWritable(-1);
@Override
protected void map(WritableComparable<?> key, VectorWritable value, Context context)
throws IOException, InterruptedException {
Vector vector = value.get();
Iterator<Vector.Element> it = vector.iterateNonZero();
while (it.hasNext()) {
Vector.Element e = it.next();
context.write(new IntWritable(e.index()), ONE);
}
context.write(TOTAL_COUNT, ONE);
}
}