permutation_test.hpp

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//============================================================================
// MCKL/include/mckl/random/permutation_test.hpp
//----------------------------------------------------------------------------
// MCKL: Monte Carlo Kernel Library
//----------------------------------------------------------------------------
// Copyright (c) 2013-2018, Yan Zhou
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are met:
//
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//   this list of conditions and the following disclaimer.
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//   Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
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//============================================================================

#ifndef MCKL_RANDOM_PERMUTATION_TEST_HPP
#define MCKL_RANDOM_PERMUTATION_TEST_HPP

#include <mckl/random/internal/common.hpp>
#include <mckl/random/chi_squared_test.hpp>

namespace mckl {

template <std::size_t T>
class PermutationTest : public ChiSquaredTest<PermutationTest<T>>
{
    static_assert(T > 0, "**PermutationTest** used with T equal to zero");

    static_assert(T <= 20, "**PermutationTest** used with T larger than 20");

  public:
    PermutationTest(std::size_t n) : n_(n), np_(static_cast<double>(n) / M_) {}

    MCKL_DEFINE_RANDOM_TEST_OPERATOR(double)

    template <typename RNGType, typename DistributionType>
    double operator()(RNGType &rng, DistributionType &distribution)
    {
        std::array<typename DistributionType::result_type, T> r;
        Vector<double> count(M_);
        std::fill(count.begin(), count.end(), 0);
        for (std::size_t i = 0; i != n_; ++i) {
            rand(rng, distribution, T, r.data());
            count[internal::permutation_index<T>(r.data())] += 1;
        }

        return this->stat(M_, count.data(), np_);
    }

    double degree_of_freedom() const { return M_ - 1; }

  private:
    static constexpr std::size_t M_ =
        internal::Factorial<std::size_t, T>::value;

    std::size_t n_;
    double np_;
}; // class PermutationTest

} // namespace mckl

#endif // MCKL_RANDOM_PERMUTATION_TEST_HPP