nearest_centroid.h

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#ifndef META_NEAREST_CENTROID_H_
#define META_NEAREST_CENTROID_H_

#include "index/inverted_index.h"
#include "index/forward_index.h"
#include "classify/classifier_factory.h"
#include "classify/classifier/classifier.h"

namespace meta
{
namespace classify
{

class nearest_centroid : public classifier
{
  public:
    const static std::string id;

    nearest_centroid(std::shared_ptr<index::inverted_index> idx,
                     std::shared_ptr<index::forward_index> f_idx);

    void train(const std::vector<doc_id>& docs) override;

    class_label classify(doc_id d_id) override;

    void reset() override;

  private:
    double cosine_sim(const std::vector<std::pair<term_id, double>>& doc,
                      const std::unordered_map<term_id, double>& centroid);

    std::shared_ptr<index::inverted_index> inv_idx_;

    std::unordered_map<class_label, std::unordered_map<term_id, double>>
        centroids_;

  public:
    class nearest_centroid_exception : public std::runtime_error
    {
      public:
        using std::runtime_error::runtime_error;
    };
};

template <>
std::unique_ptr<classifier> make_multi_index_classifier<nearest_centroid>(
    const cpptoml::table&, std::shared_ptr<index::forward_index>,
    std::shared_ptr<index::inverted_index>);
}
}
#endif