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/*!
@authors Andrei Novikov (pyclustering@yandex.ru)
@date 2014-2020
@copyright BSD-3-Clause
*/
#pragma once
#include <random>
#include <unordered_set>
#include <pyclustering/definitions.hpp>
#include <pyclustering/cluster/center_initializer.hpp>
#include <pyclustering/cluster/cluster_data.hpp>
#include <pyclustering/utils/metric.hpp>
using namespace pyclustering::utils::metric;
namespace pyclustering {
namespace clst {
/*!
@class random_center_initializer random_center_initializer.hpp pyclustering/cluster/random_center_initializer.hpp
@brief Random center initializer is for generation specified amount of random of centers for specified data.
*/
class random_center_initializer : public center_initializer {
private:
/**
*
* @brief Storage where indexes are stored.
*
*/
using index_storage = std::unordered_set<std::size_t>;
private:
std::size_t m_amount = 0;
long long m_random_state = RANDOM_STATE_CURRENT_TIME;
mutable std::mt19937 m_generator;
mutable index_storage m_available_indexes = { };
public:
/**
*
* @brief Default constructor to create random center initializer.
*
*/
random_center_initializer() = default;
/**
*
* @brief Constructor of center initializer algorithm K-Means++.
*
* @param[in] p_amount: amount of centers that should initialized.
* @param[in] p_random_state: seed for random state (by default is `RANDOM_STATE_CURRENT_TIME`, current system time is used).
*
*/
explicit random_center_initializer(const std::size_t p_amount, const long long p_random_state);
/**
*
* @brief Default copy constructor to create random center initializer.
*
*/
random_center_initializer(const random_center_initializer & p_other) = default;
/**
*
* @brief Default move constructor to create random center initializer.
*
*/
random_center_initializer(random_center_initializer && p_other) = default;
/**
*
* @brief Default destructor to destroy random center initializer.
*
*/
~random_center_initializer() = default;
public:
/**
*
* @brief Performs center initialization process in line algorithm configuration.
*
* @param[in] p_data: data for that centers are calculated.
* @param[out] p_centers: initialized centers for the specified data.
*
*/
void initialize(const dataset & p_data, dataset & p_centers) const override;
/**
*
* @brief Performs center initialization process in line algorithm configuration for
* specific range of points.
*
* @param[in] p_data: data for that centers are calculated.
* @param[in] p_indexes: point indexes from data that are defines which points should be considered
* during calculation process. If empty then all data points are considered.
* @param[out] p_centers: initialized centers for the specified data.
*
*/
void initialize(const dataset & p_data, const index_sequence & p_indexes, dataset & p_centers) const override;
private:
/**
*
* @brief Creates random center and place it to specified storage.
*
* @param[in] p_data: data for that centers are calculated.
* @param[out] p_centers: storage where new center should be placed.
*
*/
void create_center(const dataset & p_data, dataset & p_centers) const;
/**
*
* @brief Assigns seed to the random generator that is used by the algorithm.
*
*/
void initialize_random_generator();
};
}
}
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