org.apache.mahout.vectorizer.common.PartialVectorMerger.java Source code

Introduction

Here is the source code for org.apache.mahout.vectorizer.common.PartialVectorMerger.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.vectorizer.common;

import java.io.IOException;

import com.google.common.base.Preconditions;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.mahout.common.HadoopUtil;
import org.apache.mahout.math.VectorWritable;

/**
 * This class groups a set of input vectors. The Sequence file input should have a
 * {@link org.apache.hadoop.io.WritableComparable}
 * key containing document id and a {@link VectorWritable} value containing the term frequency vector. This
 * class also does normalization of the vector.
 * 
 */
public final class PartialVectorMerger {

    public static final float NO_NORMALIZING = -1.0f;

    public static final String NORMALIZATION_POWER = "normalization.power";

    public static final String DIMENSION = "vector.dimension";

    public static final String SEQUENTIAL_ACCESS = "vector.sequentialAccess";

    public static final String NAMED_VECTOR = "vector.named";

    public static final String LOG_NORMALIZE = "vector.lognormalize";

    /**
     * Cannot be initialized. Use the static functions
     */
    private PartialVectorMerger() {

    }

    /**
     * Merge all the partial {@link org.apache.mahout.math.RandomAccessSparseVector}s into the complete Document
     * {@link org.apache.mahout.math.RandomAccessSparseVector}
     * 
     * @param partialVectorPaths
     *          input directory of the vectors in {@link org.apache.hadoop.io.SequenceFile} format
     * @param output
     *          output directory were the partial vectors have to be created
     * @param baseConf
     *          job configuration
     * @param normPower
     *          The normalization value. Must be greater than or equal to 0 or equal to {@link #NO_NORMALIZING}
     * @param dimension cardinality of the vectors
     * @param sequentialAccess
     *          output vectors should be optimized for sequential access
     * @param namedVector
     *          output vectors should be named, retaining key (doc id) as a label
     * @param numReducers 
     *          The number of reducers to spawn
     */
    public static void mergePartialVectors(Iterable<Path> partialVectorPaths, Path output, Configuration baseConf,
            float normPower, boolean logNormalize, int dimension, boolean sequentialAccess, boolean namedVector,
            int numReducers) throws IOException, InterruptedException, ClassNotFoundException {
        Preconditions.checkArgument(normPower == NO_NORMALIZING || normPower >= 0,
                "If specified normPower must be nonnegative", normPower);
        Preconditions.checkArgument(
                normPower == NO_NORMALIZING || (normPower > 1 && !Double.isInfinite(normPower)) || !logNormalize,
                "normPower must be > 1 and not infinite if log normalization is chosen", normPower);

        Configuration conf = new Configuration(baseConf);
        // this conf parameter needs to be set enable serialisation of conf values
        conf.set("io.serializations", "org.apache.hadoop.io.serializer.JavaSerialization,"
                + "org.apache.hadoop.io.serializer.WritableSerialization");
        conf.setBoolean(SEQUENTIAL_ACCESS, sequentialAccess);
        conf.setBoolean(NAMED_VECTOR, namedVector);
        conf.setInt(DIMENSION, dimension);
        conf.setFloat(NORMALIZATION_POWER, normPower);
        conf.setBoolean(LOG_NORMALIZE, logNormalize);

        Job job = new Job(conf);
        job.setJobName("PartialVectorMerger::MergePartialVectors");
        job.setJarByClass(PartialVectorMerger.class);

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(VectorWritable.class);

        FileInputFormat.setInputPaths(job, getCommaSeparatedPaths(partialVectorPaths));

        FileOutputFormat.setOutputPath(job, output);

        job.setMapperClass(Mapper.class);
        job.setInputFormatClass(SequenceFileInputFormat.class);
        job.setReducerClass(PartialVectorMergeReducer.class);
        job.setOutputFormatClass(SequenceFileOutputFormat.class);
        job.setNumReduceTasks(numReducers);

        HadoopUtil.delete(conf, output);

        boolean succeeded = job.waitForCompletion(true);
        if (!succeeded) {
            throw new IllegalStateException("Job failed!");
        }
    }

    private static String getCommaSeparatedPaths(Iterable<Path> paths) {
        StringBuilder commaSeparatedPaths = new StringBuilder(100);
        String sep = "";
        for (Path path : paths) {
            commaSeparatedPaths.append(sep).append(path.toString());
            sep = ",";
        }
        return commaSeparatedPaths.toString();
    }
}