org.apache.mahout.clustering.spectral.common.VectorCache.java Source code

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Here is the source code for org.apache.mahout.clustering.spectral.common.VectorCache.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.clustering.spectral.common;

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

import com.google.common.io.Closeables;
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.SequenceFile;
import org.apache.hadoop.io.Writable;
import org.apache.mahout.common.HadoopUtil;
import org.apache.mahout.common.iterator.sequencefile.SequenceFileValueIterator;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class handles reading and writing vectors to the Hadoop
 * distributed cache. Created as a result of Eigencuts' liberal use
 * of such functionality, but available to any algorithm requiring it.
 */
public final class VectorCache {

    private static final Logger log = LoggerFactory.getLogger(VectorCache.class);

    private VectorCache() {
    }

    /**
     * 
     * @param key SequenceFile key
     * @param vector Vector to save, to be wrapped as VectorWritable
     */
    public static void save(Writable key, Vector vector, Path output, Configuration conf, boolean overwritePath,
            boolean deleteOnExit) throws IOException {

        FileSystem fs = FileSystem.get(output.toUri(), conf);
        output = fs.makeQualified(output);
        if (overwritePath) {
            HadoopUtil.delete(conf, output);
        }

        // set the cache
        DistributedCache.setCacheFiles(new URI[] { output.toUri() }, conf);

        // set up the writer
        SequenceFile.Writer writer = new SequenceFile.Writer(fs, conf, output, IntWritable.class,
                VectorWritable.class);
        try {
            writer.append(key, new VectorWritable(vector));
        } finally {
            Closeables.closeQuietly(writer);
        }

        if (deleteOnExit) {
            fs.deleteOnExit(output);
        }
    }

    /**
     * Calls the save() method, setting the cache to overwrite any previous
     * Path and to delete the path after exiting
     */
    public static void save(Writable key, Vector vector, Path output, Configuration conf) throws IOException {
        save(key, vector, output, conf, true, true);
    }

    /**
     * Loads the vector from {@link DistributedCache}. Returns null if no vector exists.
     */
    public static Vector load(Configuration conf) throws IOException {
        URI[] files = DistributedCache.getCacheFiles(conf);
        if (files == null || files.length < 1) {
            return null;
        }
        log.info("Files are: {}", Arrays.toString(files));
        return load(conf, new Path(files[0].getPath()));
    }

    /**
     * Loads a Vector from the specified path. Returns null if no vector exists.
     */
    public static Vector load(Configuration conf, Path input) throws IOException {
        log.info("Loading vector from: {}", input);
        SequenceFileValueIterator<VectorWritable> iterator = new SequenceFileValueIterator<VectorWritable>(input,
                true, conf);
        try {
            return iterator.next().get();
        } finally {
            Closeables.closeQuietly(iterator);
        }
    }
}