edu.snu.dolphin.bsp.examples.ml.sub.VectorListCodec.java Source code

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Here is the source code for edu.snu.dolphin.bsp.examples.ml.sub.VectorListCodec.java

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/*
 * Copyright (C) 2015 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.dolphin.bsp.examples.ml.sub;

import org.apache.mahout.math.DenseVector;
import org.apache.mahout.math.Vector;
import org.apache.reef.io.serialization.Codec;

import javax.inject.Inject;
import java.io.*;
import java.util.LinkedList;
import java.util.List;

/**
 * A codec that encodes and decodes a list of Vectors.
 */
public final class VectorListCodec implements Codec<List<Vector>> {

    @Inject
    public VectorListCodec() {
    }

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

        /*
         * This codec assume that vectors have the same length
         */
        int length = 0;
        for (final Vector vector : list) {
            length = vector.size();
        }

        final ByteArrayOutputStream baos = new ByteArrayOutputStream(
                Integer.SIZE + Integer.SIZE + Double.SIZE * length * list.size());

        try (final DataOutputStream daos = new DataOutputStream(baos)) {
            daos.writeInt(list.size());
            daos.writeInt(length);
            for (final Vector vector : list) {
                for (int i = 0; i < length; i++) {
                    daos.writeDouble(vector.get(i));
                }
            }
        } catch (final IOException e) {
            throw new RuntimeException(e.getCause());
        }

        return baos.toByteArray();
    }

    public List<Vector> decode(final byte[] data) {
        final ByteArrayInputStream bais = new ByteArrayInputStream(data);
        final List<Vector> resultList = new LinkedList<>();

        try (final DataInputStream dais = new DataInputStream(bais)) {
            final int listSize = dais.readInt();
            final int length = dais.readInt();
            for (int i = 0; i < listSize; i++) {
                final Vector vector = new DenseVector(length);
                for (int j = 0; j < length; j++) {
                    vector.set(j, dais.readDouble());
                }
                resultList.add(vector);
            }
        } catch (final IOException e) {
            throw new RuntimeException(e.getCause());
        }

        return resultList;
    }
}