/**
* 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.common;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.math.NamedVector;
import org.apache.mahout.math.RandomAccessSparseVector;
import org.apache.mahout.math.SequentialAccessSparseVector;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
import org.apache.mahout.math.function.Functions;
/**
* Merges partial vectors in to a full sparse vector
*/
public class PartialVectorMergeReducer extends
Reducer<WritableComparable<?>, VectorWritable, WritableComparable<?>, VectorWritable> {
private double normPower;
private int dimension;
private boolean sequentialAccess;
private boolean namedVector;
private boolean logNormalize;
@Override
protected void reduce(WritableComparable<?> key, Iterable<VectorWritable> values, Context context) throws IOException,
InterruptedException {
Vector vector = new RandomAccessSparseVector(dimension, 10);
for (VectorWritable value : values) {
vector.assign(value.get(), Functions.PLUS);
}
if (normPower != PartialVectorMerger.NO_NORMALIZING) {
if (logNormalize) {
vector = vector.logNormalize(normPower);
} else {
vector = vector.normalize(normPower);
}
}
if (sequentialAccess) {
vector = new SequentialAccessSparseVector(vector);
}
if (namedVector) {
vector = new NamedVector(vector, key.toString());
}
// drop empty vectors.
if (vector.getNumNondefaultElements() > 0) {
VectorWritable vectorWritable = new VectorWritable(vector);
context.write(key, vectorWritable);
}
}
@Override
protected void setup(Context context) throws IOException, InterruptedException {
super.setup(context);
Configuration conf = context.getConfiguration();
normPower = conf.getFloat(PartialVectorMerger.NORMALIZATION_POWER, PartialVectorMerger.NO_NORMALIZING);
dimension = conf.getInt(PartialVectorMerger.DIMENSION, Integer.MAX_VALUE);
sequentialAccess = conf.getBoolean(PartialVectorMerger.SEQUENTIAL_ACCESS, false);
namedVector = conf.getBoolean(PartialVectorMerger.NAMED_VECTOR, false);
logNormalize = conf.getBoolean(PartialVectorMerger.LOG_NORMALIZE, false);
}
}