Class: SplitCat::Experiment

Inherits:
ActiveRecord::Base
  • Object
show all
Defined in:
app/models/split_cat/experiment.rb

Constant Summary collapse

@@cache = 
HashWithIndifferentAccess.new

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.factory(name) ⇒ Object 



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# File 'app/models/split_cat/experiment.rb', line 153

def self.factory( name )
  if experiment = @@cache[ name ]
    return experiment
  end

  template = SplitCat.config.template( name )
  if experiment = Experiment.includes( :goals, :hypotheses ).find_by_name( name )
    return nil if template && !experiment.same_structure?( template )
  else
    experiment = template if template && template.save
  end

  @@cache[ name.to_sym ] = experiment

  return experiment
end

Instance Method Details

#choose_hypothesis ⇒ Object

Returns a random hypothesis with weighted probability



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# File 'app/models/split_cat/experiment.rb', line 81

def choose_hypothesis
  total = 0
  roll = Kernel.rand( total_weight ) + 1
  hypothesis = nil
  hypotheses.each do |h|
    if roll <= ( total += h.weight )
      hypothesis ||= h
    end
  end
  hypothesis ||= hypotheses.first
  return hypothesis
end

#get_hypothesis(token) ⇒ Object

Return the winner if one has been chosen. Return nil if the token can’t be found. Return the previously assigned hypothesis (or nil on error). Choose a hypothesis randomly. Record the hypothesis assignment and return it.



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# File 'app/models/split_cat/experiment.rb', line 64

def get_hypothesis( token )
  return winner if winner.present?
  return nil unless subject = Subject.find_by_token( token )

  if join = HypothesisSubject.find_by_experiment_id_and_subject_id( id, subject.id )
    hypotheses.each { |h| return h if h.id == join.hypothesis_id }
    return nil
  end

  hypothesis = choose_hypothesis
  HypothesisSubject.create( :hypothesis_id => hypothesis.id, :subject_id => subject.id, :experiment_id => id )

  return hypothesis
end

#goal_counts ⇒ Object

Returns a memoized array of goal name => hypothesis_name => subject counts



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# File 'app/models/split_cat/experiment.rb', line 17

def goal_counts
  @goal_counts ||= GoalSubject.subject_counts( self )
end

#goal_hash ⇒ Object

Return a memoized hash of goal name => goals



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# File 'app/models/split_cat/experiment.rb', line 23

def goal_hash
 return @goal_hash ||= hash_name_to_item( goals )
end

#hash_name_to_item(items) ⇒ Object 



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# File 'app/models/split_cat/experiment.rb', line 27

def hash_name_to_item( items )
  hash = HashWithIndifferentAccess.new
  items.map { |i| hash[ i.name ] = i }
  return hash
end

#hypothesis_counts ⇒ Object

Returns a memoized array of hypothesis name => subject counts



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# File 'app/models/split_cat/experiment.rb', line 35

def hypothesis_counts
  @hypothesis_counts ||= HypothesisSubject.subject_counts( self )
end

#hypothesis_hash ⇒ Object

Return a memoized hash of hypothesis name => hypotheses



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# File 'app/models/split_cat/experiment.rb', line 41

def hypothesis_hash
  return @hypothesis_hash ||= hash_name_to_item( hypotheses )
end

#record_goal(goal, token) ⇒ Object

Return true immediately if a winner has already been chosen. Return false if the goal or token can’t be found. Return true if the user isn’t in the experiment or has already recorded this goal. Record the goal and return true.



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# File 'app/models/split_cat/experiment.rb', line 102

def record_goal( goal, token )
  return true if winner_id

  return false unless goal = goal_hash[ goal ]
  return false unless subject = Subject.find_by_token( token )

  return true unless join = HypothesisSubject.find_by_experiment_id_and_subject_id( id, subject.id )
  return true if GoalSubject.find_by_goal_id_and_subject_id( goal.id, subject.id )

  GoalSubject.create( :goal_id => goal.id, :subject_id => subject.id, :experiment_id => id, :hypothesis_id => join.hypothesis_id)
  return true
end

#same_structure?(experiment) ⇒ Boolean

Returns true if the experiment has the same name, goals, and hypotheses as this one

Returns:

  • (Boolean) 


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# File 'app/models/split_cat/experiment.rb', line 117

def same_structure?( experiment )
  return nil if name.to_sym != experiment.name.to_sym
  return nil if goal_hash.keys != experiment.goal_hash.keys
  return nil if hypothesis_hash.keys != experiment.hypothesis_hash.keys
  return experiment
end

#to_csv ⇒ Object

Generates a CSV representing the experiment results

* header row of hypothesis names
* row of total subject count per hypothesis
* goal rows of subject count per hypothesis



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# File 'app/models/split_cat/experiment.rb', line 132

def to_csv
  CSV.generate do |csv|
    hypothesis_names = hypotheses.map { |h| h.name }
    hypothesis_totals = hypotheses.map { |h| hypothesis_counts[ h.name ] || 0 }

    csv << [ nil ] + hypothesis_names
    csv << [ 'total' ] + hypothesis_totals

    goals.each do |g|
      goal_totals = hypotheses.map { |h| goal_counts[ g.name ][ h.name ] || 0 }
      csv << [ g.name ] + goal_totals
    end
  end
end

#total_subjects ⇒ Object 



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# File 'app/models/split_cat/experiment.rb', line 45

def total_subjects
  @total_subjects ||= hypothesis_counts.values.inject( 0 ) { |sum,count| sum + ( count || 0 ) }
end

#total_weight ⇒ Object

Returns a memoized sum of hypothesis weights



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# File 'app/models/split_cat/experiment.rb', line 51

def total_weight
  @total_weight ||= hypotheses.inject( 0 ) { |sum,h| sum + h.weight }
end