module Stamina
  #
  # Provides a reusable module for binary classifiers. Classes including this
  # module are required to provide a label_of(string) method, returning '1' for
  # strings considered positive, and '0' fr strings considered negative.
  #
  # Note that an Automaton being a classifier it already includes this module.
  #
  module Classifier
    
    #
    # Computes a signature for a given sample (that is, an ordered set of strings).
    # The signature is a string containing 1 (considered positive, or accepted) 
    # and 0 (considered negative, or rejected), one for each string.
    #
    def signature(sample)
      signature = ''
      sample.each do |str|
        signature << label_of(str)
      end
      signature
    end
    
    # 
    # Checks if a labeled sample is correctly classified by the classifier.
    #
    def correctly_classify?(sample)
      sample.each do |str|
        label = label_of(str)
        expected = (str.positive? ? '1' : '0')
        return false unless expected==label
      end
      true
    end
    
  end # module Classifier
end # module Stamina