# File lib/ai4r/classifiers/naive_bayes.rb, line 103
      def build(data)
        raise "Error instance must be passed" unless data.is_a?(DataSet)
        raise "Data should not be empty" if data.data_items.length == 0

        initialize_domain_data(data)
        initialize_klass_index
        initialize_pc
        calculate_probabilities

        return self
      end