sampling_policy.hpp

// Copyright 2021 Arnaud Becheler    <abechele@umich.edu>
 
/*********************************************************************** * This program is free software; you can
 *redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free
 *Software Foundation; either version 2 of the License, or    * (at your option) any later version. *
 *                                                                      *
 ***************************************************************************/
 
#ifndef __SAMPLING_POLICY_H_INCLUDED__
#define __SAMPLING_POLICY_H_INCLUDED__
 
#include "editor_policy.hpp"
#include "filter_policy.hpp"
#include "memoize.hpp"
 
#include <random>
#include <utility> // std::forward, std::move
#include <vector>
 
namespace quetzal
{
namespace coalescence
{
namespace occupancy_spectrum
{
namespace sampling_policy
{
template <class FilterPolicy = filter_policy::return_always_true, class EditorPolicy = editor_policy::identity>
struct in_memoized_distribution
{
    template <typename Generator> static auto const &sample(int k, int N, Generator &g)
    {
        assert(k > 0);
        assert(N > 0);
        return memoize::memoize<FilterPolicy, EditorPolicy>(k, N)(g);
    }
}; // end class in_memoized_distribution
struct on_the_fly
{
    template <typename Generator> static auto sample(int k, int N, Generator &g)
    {
        assert(k > 0);
        assert(N > 0);
        std::vector<int> M_j(k + 1);
        std::vector<int> parents(N);
        // Populate the urns (parents) by throwing balls (lineages) at them
        std::uniform_int_distribution<int> distribution(0, N - 1);
        for (int i = 1; i <= k; ++i)
        {
            parents[distribution(g)] += 1;
        }
        // Build the occupancy spectrum by computing the occupancy numbers
        for (int it : parents)
        {
            M_j[it] += 1;
        }
        assert(M_j.size() == k + 1);
        return OccupancySpectrum(M_j, k, N);
    }
};
} // end namespace sampling_policy
} // namespace occupancy_spectrum
} // namespace coalescence
} // namespace quetzal
 
#endif