org.apache.mahout.math.RandomVector.java Source code

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Here is the source code for org.apache.mahout.math.RandomVector.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.math;

import java.util.Iterator;
import java.util.Random;

import org.apache.mahout.common.RandomUtils;
import org.apache.mahout.math.ReadOnlyVector;

import com.google.common.primitives.Longs;

/**
 * 
 * Vector with repeatable random values.
 *
 * Can only use java.util.Random as generator from RandomUtils does not honor setSeed()
 * 
 * Change to use MurmurHash projectors directly!
 */
public class RandomVector extends ReadOnlyVector {

    final private Random rnd;
    final private long baseSeed;
    final boolean gaussian;

    // required for serialization
    public RandomVector() {
        super(0);
        baseSeed = 0;
        gaussian = false;
        rnd = RandomUtils.getRandom();
    }

    /*
     * @param size
     * @param seed
     * @param gaussian
     */
    public RandomVector(int size, long seed, boolean gaussian) {
        super(size);
        baseSeed = seed;
        this.gaussian = gaussian;
        rnd = RandomUtils.getRandom(seed);
    }

    /*
     * @param size
     * @param rnd
     */
    public RandomVector(int size, Random rnd, boolean gaussian) {
        super(size);
        this.rnd = rnd;
        baseSeed = rnd.nextLong();
        this.gaussian = gaussian;
    }

    public boolean isDense() {
        return true;
    }

    public boolean isSequentialAccess() {
        return false;
    }

    public int getNumNondefaultElements() {
        return size();
    }

    public double getQuick(int index) {
        rnd.setSeed(getSeed(index));
        return gaussian ? rnd.nextGaussian() : rnd.nextDouble();
    }

    private long getSeed(int index) {
        return baseSeed + index;
    }

    public Iterator<Element> iterateNonZero() {
        return new AllIterator(this);
    }

    public Iterator<Element> iterator() {
        return new AllIterator(this);
    }

    @Override
    public boolean equals(Object o) {
        if (o.getClass() == RandomVector.class) {
            RandomVector r = (RandomVector) o;
            return size() == r.size() && baseSeed == r.baseSeed && gaussian == r.gaussian;
        }
        return false;
    }

    @Override
    public int hashCode() {
        return Longs.hashCode(baseSeed) ^ Longs.hashCode(size() ^ (gaussian ? 7 : 11));
    }

}