Class: Selection::Truncation

Inherits:

Object

• Object
• Selection::Truncation

show all

Defined in:

../lib/truncation.rb

Overview

Instance Attribute Summary (collapse)

• - (Object) population

  The population to select from.

Instance Method Summary (collapse)

• - (Truncation) initialize(ranker) constructor

  Set the ranker object (the instance of Ranking class) necessary for comparision of individuals.

• - (Object) select(how_much, population = self.population)

  Select N-best individuals from the population (N==how_much).

• - (Object) select_one(population = self.population)

  Select only the best individual from the population.

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# File '../lib/truncation.rb', line 10

def initialize ranker
  raise "Truncation: invalid Ranking object" unless ranker.kind_of? Ranking     
  @ranker = ranker
  @population = nil     
end

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# File '../lib/truncation.rb', line 17

def population
  @population
end

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# File '../lib/truncation.rb', line 20

def select( how_much, population=self.population )
  ranked = @ranker.rank( population ).map { |individual| individual.original }
  @population = population
 
  ranked[0...how_much]
end

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# File '../lib/truncation.rb', line 28

def select_one population=self.population
  select( 1, population ).first
end