Class: EvoSynth::Evaluator

Inherits:
Object
  • Object
show all
Includes:
Observable
Defined in:
lib/evosynth/core/evaluator.rb

Overview

Baseclass for all fitness evaluators. It also counts how often it was used to calculate the fitness of a given individual and how often it actually calculated the fitness.

For simple problems you just need to overwrite calculate_fitness(individual)

Obervers get notified each time calculate_and_set_fitness(individual) gets called, not on actual calculations

Direct Known Subclasses

Problems::GraphColouring, Problems::TSP

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Evaluator

Returns a new Evaluator object



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# File 'lib/evosynth/core/evaluator.rb', line 50

def initialize
  reset_counters
end

Instance Attribute Details

#calculated ⇒ Object (readonly)

How often did the Evaluator actually calculate a fitness value



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# File 'lib/evosynth/core/evaluator.rb', line 46

def calculated
  @calculated
end

#called ⇒ Object (readonly)

How often did the Evaluator return a fitness value



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# File 'lib/evosynth/core/evaluator.rb', line 42

def called
  @called
end

Instance Method Details

#calculate_and_set_fitness(individual) ⇒ Object

Calculates and sets the fitness of the given individual if the individual has changed, otherwise it just returns the cached fitness of the individual



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# File 'lib/evosynth/core/evaluator.rb', line 57

def calculate_and_set_fitness(individual)
  @called += 1

  if individual.changed?
    @calculated += 1
    individual.fitness = calculate_fitness(individual)
  end

  changed
  notify_observers self, @called
  individual.fitness
end

#calculate_and_set_initial_fitness(individual) ⇒ Object

Calculates and sets the initial fitness of the given individual.



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# File 'lib/evosynth/core/evaluator.rb', line 72

def calculate_and_set_initial_fitness(individual)
  @called += 1
  @calculated += 1

  individual.fitness = calculate_initial_fitness(individual)

  changed
  notify_observers self, @called
  individual.fitness
end

#calculate_fitness(individual) ⇒ Object

This function is actually used to calculate the fitness of a individual. It’s the “fitness function”.

Raises:

  • (NotImplementedError) 


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# File 'lib/evosynth/core/evaluator.rb', line 85

def calculate_fitness(individual)
  raise NotImplementedError, "please implement calculate_fitness!"
end

#calculate_initial_fitness(individual) ⇒ Object

This function is used to calculate an intitial fitness value for a individual. Calls calculate_fitness by default.



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# File 'lib/evosynth/core/evaluator.rb', line 91

def calculate_initial_fitness(individual)
  calculate_fitness(individual)
end

#reset_counters ⇒ Object

Reset the called/calculated counters of the Evaluator



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# File 'lib/evosynth/core/evaluator.rb', line 97

def reset_counters
  @called = 0
  @calculated = 0
end

#to_s ⇒ Object

Returns a human readable reprasentation of the Evaluator



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# File 'lib/evosynth/core/evaluator.rb', line 104

def to_s
  "Evaluator <called: #{@called}, calculated: #{@calculated}>"
end