Class: Util::PipedIndividual

Inherits:
Individual show all
Includes:
AlpsIndividual
Defined in:
../lib/piped_individual.rb

Overview

This is the universally configurable subclass of the Individual class, for the use with the WorkPipes evaluator. The user can specify multiple objectives and the kind of their optimisation, describe the item names and types of the evaluator’s output, define the stopping condition, etc. All the configuration is done via ConfigYaml class using the yaml file, without the need of writing domain-specific class for each task.

Defined Under Namespace

Classes: PipedIndSchema

Constant Summary

@@phenotype_mark = 
''
@@batch_mark = 
nil

Instance Attribute Summary

Attributes inherited from Individual

#complexity, #genotype, #phenotype, #track_support, #used_length

Class Method Summary (collapse)

Instance Method Summary (collapse)

Methods included from AlpsIndividual

#age, age_gap, age_limits, aging_scheme, #layer, layers, #parents

Methods inherited from Individual

#shorten_chromozome=, #valid?

Constructor Details

- (PipedIndividual) initialize(mapper, genotype)

Create the new phenotype, based on the genotype, using the mapper. 



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# File '../lib/piped_individual.rb', line 22

def initialize( mapper, genotype )
  super
  @phenotype += @@phenotype_mark unless @phenotype.nil?
end

Class Method Details

+ (Object) batch_mark

Return the text separating the batch of pipe inputs for one WorkPipes#run call. This text is set by the PipedIndividual.mark_batch static method. 



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# File '../lib/piped_individual.rb', line 157

def PipedIndividual.batch_mark
  @@batch_mark
end

+ (Object) mark_batch(mark)

Set the optional text separating each WorkPipes#run call in the pipe’s input, if needed by the pipe process. This text is retrieved by the WorkPipes’s instance using PipedIndividual#batch_mark method, defaulting to ’’. 



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# File '../lib/piped_individual.rb', line 151

def PipedIndividual.mark_batch mark
  @@batch_mark = mark
end

+ (Object) mark_phenotype(mark)

Set the optional text separating each phenotype in the pipe’s input, if needed by the pipe process. This text is attached to the end of :phenotype attribute, defaulting to ’’. 



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# File '../lib/piped_individual.rb', line 145

def PipedIndividual.mark_phenotype mark
  @@phenotype_mark = mark
end

+ (Object) pareto(par)

Shorthand for the PipedIndividual.pareto_core( Moea::Pareto, par ) 



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# File '../lib/piped_individual.rb', line 94

def PipedIndividual.pareto par
  PipedIndividual.pareto_core( Moea::Pareto, par )
end

+ (Object) pareto_core(klass, par)

Describe the optimisation objectives for the Pareto module (see). The outputs argument is to be the hash describing each objective. Each key-value pair represents one objective. The hash key is the name (symbol) of the objective, the value is the ‘direction’ of the optimisation, ie. either ‘minimize’ or ‘maximize’ The klass is either Moea::Pareto or Moea::WeakPareto, specifying the strong or weak pareto definition. 


  objectives = {} 
  objectives[ :amount ] = 'minimize'
  objectives[ :score ] = 'maximize'
  PipedIndividual.pareto objectives


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# File '../lib/piped_individual.rb', line 114

def PipedIndividual.pareto_core( klass, par )
  include klass     
  Moea::Pareto.clear_objectives PipedIndividual
  @@thresh_over = {}

  par.each_pair do |sym,dir|
    attr_accessor sym unless method_defined? sym

    case dir.to_s
      when 'maximize'
        Moea::Pareto.maximize( PipedIndividual, sym )
        @@thresh_over[ sym ] = true
      when 'minimize'
        Moea::Pareto.minimize( PipedIndividual, sym )
        @@thresh_over[ sym ] = false
      else
        raise "PipedIndividual:wrong objective direction '#{dir}' for objective '#{sym}'" 
    end

  end
end

+ (Object) pipe_output(outputs)

Specify the schema for the parse= method (see). The outputs argument is to be the array of hashes describing each item of the pipe output, in the correct order. Each hash contains only one key-value pair. The hash key represents the name (symbol) of the attribute (usually the objective), the value is the conversion method for parsing the text to the correct numeric type.

For example: 


  schema = []
  schema << {:amount => 'to_f'}
  schema << {:score => 'to_i'}
  PipedIndividual.pipe_output schema

  individual.row = '1243.32 42'  # suppose the pipe returns 2 values per one individual's evaluation
  individual.amount  # >> 1243.32
  individual.score   # >> 42


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# File '../lib/piped_individual.rb', line 73

def PipedIndividual.pipe_output outputs
  
  @@schema = []     

  outputs.each do |item|
    item.each_pair do |sym,conv|

      attr_accessor sym unless method_defined? sym

      @@schema << PipedIndSchema.new( sym, conv )
    end
  end

end

+ (Object) pipe_schema

Report symbols (meaning of the output items), previously entered by PipedIndividual.pipe_output call. 



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# File '../lib/piped_individual.rb', line 89

def PipedIndividual.pipe_schema
  @@schema.map { |item| item.symb }
end

+ (Boolean) symbol_maximized?(symbol)

Return true if the symbol would be Pareto-maximized

Returns:

  • (Boolean) 


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# File '../lib/piped_individual.rb', line 137

def PipedIndividual.symbol_maximized? symbol
  result = @@thresh_over.fetch( symbol, nil )
  raise "PipedIndividual: symbol '#{symbol}' not known" if result.nil?
  result
end

+ (Object) thresholds(thresh)

Specify the components of the stopping_condition method (see). The thresh argument is the hash describing each attribute of the stopping expression. The hash key represents the name (symbol) of the objective, the value is the threshold value used for comparision. Note the ‘direction’ of the optimisation has to be set by the PipedIndividual.pareto_core static method.

For example: 


  objectives = {} 
  objectives[ :amount ] = 'minimize'
  objectives[ :score ] = 'maximize'
  PipedIndividual.pareto objectives

  condition = {}
  condition[ :amount ] = 5435.34
  condition[ :score ] = 61
  PipedIndividual.thresholds condition
  
  individual.amount = 8430.2
  individual.score = 144
  individual.stopping_condition # >> false (individual.amount <= 5435.34 and individual.score > 61)


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# File '../lib/piped_individual.rb', line 181

def PipedIndividual.thresholds thresh
  @@thresh_values = thresh
end

+ (Object) weak_pareto(par)

Shorthand for the PipedIndividual.pareto_core( Moea::WeakPareto, par ) 



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# File '../lib/piped_individual.rb', line 99

def PipedIndividual.weak_pareto par
  PipedIndividual.pareto_core( Moea::WeakPareto, par )
end

Instance Method Details

- (Object) parse=(row)

Take the result of the phenotype evaluation and process it. The text row argument consists of one or more values, separated by the space. Meaning of these values and their type conversions must be specified by the PipedIndividual.pipe_output static method, before calling parse=.

For example: 


  individual.row = '1243.32 42'  # suppose the pipe returns 2 values per one individual's evaluation


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# File '../lib/piped_individual.rb', line 34

def parse= row
  items = row.gsub(/^\s+/,'').gsub(/\s+$/,'').split( /\s+/ )
  raise "PipedIndividual: parse= expecting #{@@schema.size} items, got #{items.size}" unless @@schema.size == items.size

  items.each_with_index do |item,index|
    value = item.send( @@schema[index].conversion )
    send( "#{@@schema[index].symb}=", value )
  end
end

- (Object) stopping_condition

This method tests the individual for the meeting of stopping condition. If all conditions are met (ie. in the case of the ‘winner’ individual), the stopping_condition returns true. Conditions have to be set by the PipedIndividual.thresholds static method. 



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# File '../lib/piped_individual.rb', line 47

def stopping_condition
  @@thresh_values.each_pair do |symb,value|
    max = @@thresh_over.fetch( symb, nil )

    raise "PipedIndividual: optimisation direction not known for the objective '#{symb}'" if max.nil?
    return false if max ? ( send(symb) < value ) : ( send(symb) > value )
  end

  true
end