edu.snu.cms.reef.ml.kmeans.groupcomm.subs.CentroidListCodec.java Source code

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Here is the source code for edu.snu.cms.reef.ml.kmeans.groupcomm.subs.CentroidListCodec.java

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/**
 * Copyright (C) 2014 Seoul National University
 *
 * Licensed 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 edu.snu.cms.reef.ml.kmeans.groupcomm.subs;

import org.apache.mahout.math.DenseVector;
import org.apache.mahout.math.Vector;
import org.apache.reef.io.serialization.Codec;
import edu.snu.cms.reef.ml.kmeans.data.Centroid;

import javax.inject.Inject;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * Codec for encoding and decoding a KMeansCentroid List
 */
public final class CentroidListCodec implements Codec<List<Centroid>> {

    @Inject
    public CentroidListCodec() {
    }

    @Override
    public final byte[] encode(final List<Centroid> list) {

        /* This codec does not assume consistent centroid vector sizes(dimensions).
         * Therefore to specify the initial data size,
         * a quick iteration over the input list to compute
         * the sums of vector sizes is required.
         */
        int vectorSizeSum = 0;
        for (final Centroid centroid : list) {
            vectorSizeSum += centroid.vector.size();
        }

        final ByteArrayOutputStream baos = new ByteArrayOutputStream(
                Integer.SIZE + Integer.SIZE * 2 * list.size() + Double.SIZE * vectorSizeSum);
        try (final DataOutputStream daos = new DataOutputStream(baos)) {
            daos.writeInt(list.size());
            for (final Centroid centroid : list) {
                daos.writeInt(centroid.getClusterId());
                daos.writeInt(centroid.vector.size());

                for (int j = 0; j < centroid.vector.size(); j++) {
                    daos.writeDouble(centroid.vector.get(j));
                }

            }

        } catch (final IOException e) {
            throw new RuntimeException(e.getCause());
        }

        return baos.toByteArray();
    }

    @Override
    public final List<Centroid> decode(final byte[] data) {
        final ByteArrayInputStream bais = new ByteArrayInputStream(data);
        final List<Centroid> list = new ArrayList<>();

        try (final DataInputStream dais = new DataInputStream(bais)) {
            final int listSize = dais.readInt();

            for (int i = 0; i < listSize; i++) {
                final int clusterId = dais.readInt();
                final int vectorSize = dais.readInt();
                final Vector vector = new DenseVector(vectorSize);

                for (int j = 0; j < vectorSize; j++) {
                    vector.set(j, dais.readDouble());
                }

                list.add(new Centroid(clusterId, vector));
            }

        } catch (final IOException e) {
            throw new RuntimeException(e.getCause());
        }

        return list;
    }
}