lda_gibbs.h

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#ifndef META_LDA_GIBBS_H_
#define META_LDA_GIBBS_H_

#include <random>

#include "stats/multinomial.h"
#include "topics/lda_model.h"
#include "util/dense_matrix.h"

namespace meta
{
namespace topics
{

class lda_gibbs : public lda_model
{
  public:
    lda_gibbs(std::shared_ptr<index::forward_index> idx, uint64_t num_topics,
              double alpha, double beta);

    virtual ~lda_gibbs() = default;

    virtual void run(uint64_t num_iters, double convergence = 1e-6);

  protected:
    topic_id sample_topic(term_id term, doc_id doc);

    virtual double compute_sampling_weight(term_id term, doc_id doc,
                                           topic_id topic) const;

    virtual double
        compute_term_topic_probability(term_id term,
                                       topic_id topic) const override;

    virtual double compute_doc_topic_probability(doc_id doc,
                                                 topic_id topic) const override;

    virtual void initialize();

    virtual void perform_iteration(uint64_t iter, bool init = false);

    virtual void decrease_counts(topic_id topic, term_id term, doc_id doc);

    virtual void increase_counts(topic_id topic, term_id term, doc_id doc);

    double corpus_log_likelihood() const;

    lda_gibbs& operator=(const lda_gibbs&) = delete;

    lda_gibbs(const lda_gibbs& other) = delete;

    std::vector<std::vector<topic_id>> doc_word_topic_;

    std::vector<stats::multinomial<term_id>> phi_;

    std::vector<stats::multinomial<topic_id>> theta_;

    std::mt19937_64 rng_;
};
}
}

#endif