HaltonSequence.cpp

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/* Author: Leonard Bruns */
 
#include "ompl/base/samplers/deterministic/HaltonSequence.h"
#include "ompl/util/Console.h"
#include <iostream>
#include <cmath>
#include <map>
#include <boost/math/special_functions/prime.hpp>
 
namespace ompl
{
    namespace base
    {
        HaltonSequence1D::HaltonSequence1D() : i_(1), base_(2)
        {
        }
 
        HaltonSequence1D::HaltonSequence1D(unsigned int base) : i_(1), base_(base)
        {
        }
 
        void HaltonSequence1D::setBase(unsigned int base)
        {
            base_ = base;
        }
 
        double HaltonSequence1D::sample()
        {
            double f = 1, r = 0;
            unsigned int i = i_;
 
            while (i > 0)
            {
                f /= base_;
                r += f * (i % base_);
                i = std::floor(i / base_);
            }
 
            ++i_;
            return r;
        }
 
        HaltonSequence::HaltonSequence(unsigned int dimensions)
          : DeterministicSequence(dimensions), halton_sequences_1d_(dimensions)
        {
            setBasesToPrimes();
        }
 
        HaltonSequence::HaltonSequence(unsigned int dimensions, std::vector<unsigned int> bases)
          : DeterministicSequence(dimensions), halton_sequences_1d_(dimensions)
        {
            if (bases.size() != dimensions)
            {
                OMPL_WARN("Number of bases does not match dimensions. Using first n primes instead.");
            }
            else
            {
                int i = 0;
                for (auto base : bases)
                {
                    halton_sequences_1d_[i].setBase(base);
                    i++;
                }
            }
        }
 
        std::vector<double> HaltonSequence::sample()
        {
            std::vector<double> samples;
            for (auto &seq : halton_sequences_1d_)
            {
                samples.push_back(seq.sample());
            }
            return samples;
        }
 
        void HaltonSequence::setBasesToPrimes()
        {
            // set the base of the halton sequences to the first n prime numbers, where n is dimensions
            unsigned int current = 2;
            for (unsigned int i = 0; i < dimensions_; i++)
            {
                current = boost::math::prime(i);
                halton_sequences_1d_[i].setBase(current);
            }
        }
    }  // namespace base
}  // namespace ompl