Module: ActsAsMeritocracy::InstanceMethods

Defined in:
lib/acts_as_meritocracy/model.rb

Instance Method Summary collapse

Instance Method Details

#best_decision(tie_method = "random") ⇒ Object

majority vote (get the decision with the higher number of votes)



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# File 'lib/acts_as_meritocracy/model.rb', line 65

def best_decision(tie_method="random")
  best=nil
  tie=[]
  nb_categories=0
  self.vote_distribution.each { |category|
    if ((best.nil?) || (category.freq>best.freq))
      best=category
      tie=[]
      tie<<category
      # managing tie
    elsif (category.freq==best.freq)
      tie<<category
    end
    nb_categories=nb_categories+1
  }

  # tie detected
  if (tie.size>1)
    case (tie_method)
      when "random" then
        tie[rand(tie.size)].vote
      when "nodecision" then
        nil
    end
    # no vote
  elsif (best.nil?)
    nil
    # get the most chosen category
  else
    best.vote
  end
end

#consensus(method = "kappa") ⇒ Object

Consensus score using the vote distribubtion very high consensus=1 , very low consensus=0 could be used as an indicator to measure the difficulty of users to take collectively a decision 2 methods are proposed

  • Entropy

  • Fleiss Kappa taking into account the weight (NOTE: I removed the pb of chance in the computation)



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# File 'lib/acts_as_meritocracy/model.rb', line 104

def consensus(method="kappa")
  consensus= case method
               when "entropy" then
                 dist=self.vote_distribution
                 nb_votes=dist.inject(0) { |sum, category| sum+category.freq }.to_f
                 h=self.vote_distribution.inject(0) { |h, category|
                   p_j=category.freq.to_f/nb_votes
                   h + p_j*Math.log(p_j)
                 }
                 h=[h, -1].max
                 1+h

               when "kappa" then
                 dist=self.vote_distribution
                 nb_votes=dist.inject(0) { |sum, category| sum+category.freq }.to_f
                 fact=dist.inject(0) { |fact, category|
                   fact+category.freq**2
                 }
                 (fact-nb_votes)/(nb_votes*(nb_votes-1))
               else
                 0
             end
  consensus
end

#nb_votes(weighted = true) ⇒ Object

number of votes taking into account (or not) the weight of the vote 1 vote with vote_weight=2 ==> 2 votes



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# File 'lib/acts_as_meritocracy/model.rb', line 51

def nb_votes(weighted=true)
  if (weighted)
    self.votes.sum('vote_weight')
  else
    self.votes.count
  end
end

#submit_vote(user, vote, vote_weight = 1) ⇒ Object

submit or update the vote of someone



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# File 'lib/acts_as_meritocracy/model.rb', line 130

def submit_vote(user, vote, vote_weight=1)

  #check existence
  v=Vote.where(:voter_id=>user.id, :voteable_id=>self.id, :voteable_type => self.class.name).first

  #if not create new vote
  if (v.nil?)
    v=Vote.create(:voter=>user,
                  :voteable=>self,
                  :vote=>vote,
                  :vote_weight=>vote_weight)
    #modify existing vote
  else
    v.update_attributes(:vote=>vote, :vote_weight=>vote_weight)
  end
  v
end

#vote_distribution ⇒ Object

retrieve the vote distribution



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# File 'lib/acts_as_meritocracy/model.rb', line 60

def vote_distribution
  Vote.select("vote, sum(vote_weight) as freq").where(:voteable_id=>self.id).group(:vote).order("freq DESC")
end

#voted_by?(user) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/acts_as_meritocracy/model.rb', line 45

def voted_by?(user)
  self.votes.exists?(:voter_id=>user.id)
end