org.apache.mahout.utils.vectors.common.PartialVectorMergeReducer.java Source code

Introduction

Here is the source code for org.apache.mahout.utils.vectors.common.PartialVectorMergeReducer.java

Source

/**
 * 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.utils.vectors.common;

import java.io.IOException;
import java.util.Iterator;

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;

/**
 * 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;

    @Override
    protected void reduce(WritableComparable<?> key, Iterable<VectorWritable> values, Context context)
            throws IOException, InterruptedException {

        Vector vector = new RandomAccessSparseVector(dimension, 10);
        for (VectorWritable value : values) {
            value.get().addTo(vector);
        }
        if (normPower != PartialVectorMerger.NO_NORMALIZING) {
            vector = vector.normalize(normPower);
        }
        if (sequentialAccess) {
            vector = new SequentialAccessSparseVector(vector);
        }
        VectorWritable vectorWritable = new VectorWritable(new NamedVector(vector, key.toString()));
        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);
    }

}