KMeans.hpp

#pragma once
/* (C) 2021 Roman Werpachowski. */
#include "Clustering.hpp"
#include <vector>
#include <utility>
#include <Eigen/Core>
#include "dll.hpp"
 
namespace ml
{
    namespace Clustering
    {
        class KMeans : public Model
        {
        public:
            DLL_DECLSPEC KMeans(unsigned int number_clusters);
 
            DLL_DECLSPEC bool fit(Eigen::Ref<const Eigen::MatrixXd> data) override;
 
            unsigned int number_clusters() const override
            {
                return num_clusters_;
            }
 
            const std::vector<unsigned int>& labels() const override
            {
                return labels_;
            }
 
            const Eigen::MatrixXd& centroids() const override
            {
                return centroids_;
            }
 
            DLL_DECLSPEC void set_seed(unsigned int seed);
 
            DLL_DECLSPEC void set_absolute_tolerance(double absolute_tolerance);
 
            DLL_DECLSPEC void set_maximum_steps(unsigned int maximum_steps);
 
            DLL_DECLSPEC void set_number_initialisations(unsigned int number_initialisations);
 
            DLL_DECLSPEC void set_centroids_initialiser(std::shared_ptr<const CentroidsInitialiser> centroids_initialiser);
 
            void set_verbose(bool verbose)
            {
                verbose_ = verbose;
            }
 
            DLL_DECLSPEC std::pair<unsigned int, double> assign_label(Eigen::Ref<const Eigen::VectorXd> x) const;
 
            double inertia() const
            {
                return inertia_;
            }
 
            bool converged() const override
            {
                return converged_;
            }
        private:
            std::vector<unsigned int> labels_;
            std::vector<unsigned int> old_labels_;
            Eigen::MatrixXd centroids_;
            Eigen::MatrixXd old_centroids_;
            Eigen::VectorXd work_vector_;
            std::default_random_engine prng_;
            std::shared_ptr<const CentroidsInitialiser> centroids_initialiser_;
            double absolute_tolerance_;
            double inertia_;
            unsigned int maximum_steps_;
            unsigned int num_inits_;
            unsigned int num_clusters_;
            bool verbose_;
            bool converged_;
 
            bool fit_once(Eigen::Ref<const Eigen::MatrixXd> data);
 
            void assignment_step(Eigen::Ref<const Eigen::MatrixXd> data);
 
            void update_step(Eigen::Ref<const Eigen::MatrixXd> data);
        };
    }
}