org.apache.mahout.utils.vectors.tfidf.TFIDFPartialVectorReducer.java Source code

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Here is the source code for org.apache.mahout.utils.vectors.tfidf.TFIDFPartialVectorReducer.java

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/**
 * 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.tfidf;

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

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.filecache.DistributedCache;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.SequenceFile;
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.map.OpenIntLongHashMap;
import org.apache.mahout.utils.vectors.TFIDF;
import org.apache.mahout.utils.vectors.common.PartialVectorMerger;

/**
 * Converts a document in to a sparse vector
 */
public class TFIDFPartialVectorReducer
        extends Reducer<WritableComparable<?>, VectorWritable, WritableComparable<?>, VectorWritable> {

    private final OpenIntLongHashMap dictionary = new OpenIntLongHashMap();

    private final TFIDF tfidf = new TFIDF();

    private int minDf = 1;

    private int maxDfPercent = 99;

    private long vectorCount = 1;

    private long featureCount;

    private boolean sequentialAccess;

    @Override
    protected void reduce(WritableComparable<?> key, Iterable<VectorWritable> values, Context context)
            throws IOException, InterruptedException {
        Iterator<VectorWritable> it = values.iterator();
        if (!it.hasNext()) {
            return;
        }
        Vector value = it.next().get();
        Iterator<Vector.Element> it1 = value.iterateNonZero();
        Vector vector = new RandomAccessSparseVector((int) featureCount, value.getNumNondefaultElements());
        while (it1.hasNext()) {
            Vector.Element e = it1.next();
            if (!dictionary.containsKey(e.index())) {
                continue;
            }
            long df = dictionary.get(e.index());
            if (df / vectorCount > maxDfPercent) {
                continue;
            }
            if (df < minDf) {
                df = minDf;
            }
            vector.setQuick(e.index(),
                    tfidf.calculate((int) e.get(), (int) df, (int) featureCount, (int) vectorCount));
        }
        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);
        try {
            Configuration conf = context.getConfiguration();
            URI[] localFiles = DistributedCache.getCacheFiles(conf);
            if (localFiles == null || localFiles.length < 1) {
                throw new IllegalArgumentException("missing paths from the DistributedCache");
            }

            vectorCount = conf.getLong(TFIDFConverter.VECTOR_COUNT, 1);
            featureCount = conf.getLong(TFIDFConverter.FEATURE_COUNT, 1);
            minDf = conf.getInt(TFIDFConverter.MIN_DF, 1);
            maxDfPercent = conf.getInt(TFIDFConverter.MAX_DF_PERCENTAGE, 99);
            sequentialAccess = conf.getBoolean(PartialVectorMerger.SEQUENTIAL_ACCESS, false);

            Path dictionaryFile = new Path(localFiles[0].getPath());
            FileSystem fs = dictionaryFile.getFileSystem(conf);
            SequenceFile.Reader reader = new SequenceFile.Reader(fs, dictionaryFile, conf);
            IntWritable key = new IntWritable();
            LongWritable value = new LongWritable();

            // key is feature, value is the document frequency
            while (reader.next(key, value)) {
                dictionary.put(key.get(), value.get());
            }
        } catch (IOException e) {
            throw new IllegalStateException(e);
        }
    }

}