pairwise_comparable.rb

# Copyright (c) 2012 Medhi Widjaja

module AnalysisMethods
  module Ahp
    module PairwiseComparable
      class PairwiseComparison
        include Mongoid::Document
        
        field :id1,   type: Moped::BSON::ObjectId
        field :id2,   type: Moped::BSON::ObjectId
        field :value, type: Float
        
        embedded_in :pairwise_comparable

        def slider_value
          self.value
        end

        def comparison_value
          self.value > 0 ? 1/(value+1) : -value+1
        end

        def convert
          v = self.value.to_r
          w = v >= 1 ? -v+1 : v.denominator-1
          w.to_f
        end
      end
    end
  end
end