Class: Schulze::Ballot

Inherits:
Object
  • Object
show all
Defined in:
lib/schulze/ballot.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Ballot

Returns a new instance of Ballot.



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# File 'lib/schulze/ballot.rb', line 16

def initialize
  @choices = Hash.new(1e9)
end

Class Method Details

.new_from_filename(filename) ⇒ Object 



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# File 'lib/schulze/ballot.rb', line 5

def self.new_from_filename filename
  new.tap do |ballot|
    File.open(filename, 'r') do |io|
      io.each_line do |line|
        chunks = line.split
        ballot.add_choice(chunks.first.to_i, chunks.last)
      end
    end
  end
end

Instance Method Details

#add_choice(ordering, name) ⇒ Object 



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# File 'lib/schulze/ballot.rb', line 20

def add_choice ordering, name
  @choices[name] = ordering
end

#candidates ⇒ Object 



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# File 'lib/schulze/ballot.rb', line 24

def candidates
  @choices.keys
end

#preference_matrix(all_candidates) ⇒ Object 



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# File 'lib/schulze/ballot.rb', line 28

def preference_matrix all_candidates
  matrix = Matrix.zero(all_candidates.size)
  Matrix.build(all_candidates.size) do |row, col|
    if row == col
      0
    else
      a, b = all_candidates[row], all_candidates[col]
      prefers?(a, b) ? 1 : 0
    end
  end
end

#prefers?(a, b) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/schulze/ballot.rb', line 40

def prefers? a, b
  @choices[a] < @choices[b]
end

#to_s ⇒ Object 



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# File 'lib/schulze/ballot.rb', line 44

def to_s
  "Ballot:\n" + @choices.to_a.map(&:inspect).join("\n")
end