edu.snu.cms.reef.ml.kmeans.data.VectorSum.java Source code

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Here is the source code for edu.snu.cms.reef.ml.kmeans.data.VectorSum.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.data;

import org.apache.mahout.math.DenseVector;
import org.apache.mahout.math.Vector;

import java.io.Serializable;
import java.util.Formatter;
import java.util.Locale;

/**
 * This class represents a set of vectors by their sum and count.
 */
public class VectorSum implements Serializable {

    public Vector sum;
    public int count;

    /**
     * We may select whether to create a deep copy of @member sum, or just a reference.
     */
    public VectorSum(final Vector sum, final int count, final boolean isDeepCopy) {
        this.count = count;
        if (isDeepCopy) {
            final Vector newSum = new DenseVector(sum.size());
            for (int i = 0; i < newSum.size(); i++) {
                newSum.set(i, sum.get(i));
            }
            this.sum = newSum;
        } else {
            this.sum = sum;
        }
    }

    public VectorSum(final Vector sum, final int count) {
        this(sum, count, false);
    }

    /**
     * A deep copy constructor
     */
    public VectorSum(final VectorSum vectorSum) {
        this(vectorSum.sum, vectorSum.count, true);
    }

    public final void add(VectorSum vectorSum) {
        this.sum = this.sum.plus(vectorSum.sum);
        this.count += vectorSum.count;
    }

    public final void add(Vector vector) {
        this.sum = this.sum.plus(vector);
        this.count++;
    }

    public final void addSums(Iterable<VectorSum> vectorSums) {
        for (final VectorSum vectorSum : vectorSums) {
            this.add(vectorSum);
        }
    }

    public final void addVectors(Iterable<Vector> vectors) {
        for (final Vector vector : vectors) {
            this.add(vector);
        }
    }

    public final static VectorSum addAllSums(Iterable<VectorSum> vectorSums) {
        VectorSum totalVectorSum = null;
        for (final VectorSum vectorSum : vectorSums) {
            if (totalVectorSum == null) {
                totalVectorSum = new VectorSum(vectorSum);
                continue;
            }

            totalVectorSum.add(vectorSum);
        }

        return totalVectorSum;
    }

    public final static VectorSum addAllVectors(Iterable<Vector> vectors) {
        VectorSum vectorSum = null;
        for (final Vector vector : vectors) {
            if (vectorSum == null) {
                vectorSum = new VectorSum(vector, 1, true);
                continue;
            }

            vectorSum.add(vector);
        }

        return vectorSum;
    }

    public final Vector computeVectorMean() {
        final Vector mean = new DenseVector(sum.size());
        for (int i = 0; i < mean.size(); i++) {
            mean.set(i, sum.get(i) / count);
        }
        return mean;
    }

    @SuppressWarnings("boxing")
    @Override
    public String toString() {
        final StringBuilder b = new StringBuilder("VectorSum(");
        try (final Formatter formatter = new Formatter(b, Locale.US)) {
            formatter.format("Count %d, ", count);

            if (sum == null || sum.size() == 0) {
                formatter.format("Empty)");
            } else {
                for (int i = 0; i < sum.size() - 1; ++i) {
                    formatter.format("%1.3f, ", sum.get(i));
                }
                formatter.format("%1.3f)", sum.get(sum.size() - 1));
            }
        }

        return b.toString();
    }
}