RandomNumberGenerator.hpp

/*

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*/

#ifndef RANDOMNUMBERGENERATORS_HPP_
#define RANDOMNUMBERGENERATORS_HPP_

#include <sstream>
#include <boost/shared_ptr.hpp>
#include <boost/version.hpp>


#if BOOST_VERSION < 105600
// Forward compatibility with Boost 1.56 onwards
#include "Boost156NormalDistribution.hpp"
#endif

#include <boost/random.hpp>

#include "ChasteSerialization.hpp"
#include "SerializableSingleton.hpp"
#include <boost/serialization/split_member.hpp>

class RandomNumberGenerator : public SerializableSingleton<RandomNumberGenerator>
{
private:
    boost::mt19937 mMersenneTwisterGenerator;

    // If you add any more generators below, then remember to add lines for them in the Reseed() method too.

    boost::variate_generator<boost::mt19937& , boost::uniform_real<> > mGenerateUnitReal;

#if BOOST_VERSION < 105600  //#2585
    boost::variate_generator<boost::mt19937& , boost::random::normal_distribution_v156<> > mGenerateStandardNormal;
#else
    boost::variate_generator<boost::mt19937& , boost::normal_distribution<> > mGenerateStandardNormal;
#endif

    static RandomNumberGenerator* mpInstance;

    friend class boost::serialization::access;
    template<class Archive>
    void save(Archive & archive, const unsigned int version) const
    {
        std::stringstream rng_internals;
        rng_internals << mMersenneTwisterGenerator;
        std::string rng_internals_string = rng_internals.str();
        archive & rng_internals_string;

        std::stringstream normal_internals;
#if BOOST_VERSION < 105600  //#2585
        const boost::random::normal_distribution_v156<>& r_normal_dist = mGenerateStandardNormal.distribution();
#else
        const boost::normal_distribution<>& r_normal_dist = mGenerateStandardNormal.distribution();
#endif
        normal_internals << r_normal_dist;
        std::string normal_internals_string = normal_internals.str();
        archive & normal_internals_string;
    }

    template<class Archive>
    void load(Archive & archive, const unsigned int version)
    {
        std::string rng_internals_string;
        archive & rng_internals_string;
        std::stringstream rng_internals(rng_internals_string);
        rng_internals >> mMersenneTwisterGenerator;

        std::string normal_internals_string;
        archive & normal_internals_string;
        std::stringstream normal_internals(normal_internals_string);
        normal_internals >> mGenerateStandardNormal.distribution();
    }
    BOOST_SERIALIZATION_SPLIT_MEMBER()

protected:

    RandomNumberGenerator();

public:

    double StandardNormalRandomDeviate();

    double NormalRandomDeviate(double mean, double stdDev);

    double ranf();

    double GammaRandomDeviate(double shape, double scale);

    double ExponentialRandomDeviate(double scale);

    unsigned randMod(unsigned base);

    template <class T>
    void Shuffle(std::vector<boost::shared_ptr<T> >& rValues)
    {
        unsigned num = rValues.size();
        if (num == 0)
        {
            return;
        }
        for (unsigned end=num-1; end>0; end--)
        {
            // Pick a random integer from {0,..,end}
            unsigned k = RandomNumberGenerator::Instance()->randMod(end+1);
            boost::shared_ptr<T> temp = rValues[end];
            rValues[end] = rValues[k];
            rValues[k] = temp;
        }
    }

    void Shuffle(unsigned num, std::vector<unsigned>& rValues);

    static RandomNumberGenerator* Instance();

    static void Destroy();

    void Reseed(unsigned seed);
};

#endif /*RANDOMNUMBERGENERATORS_HPP_*/