配列の要素をランキングする

ranking.rb

class Array
  def ranks
    rank = self.sort.reverse
    self.map {|n| rank.index(n) + 1 }
  end
end

describe Array do
  describe '#ranks' do
    it { [100, 80, 90, 90, 90, 70, 70, 80].ranks.should == [1, 5, 2, 2, 2, 7, 7, 5] }
  end
end

% rspec ranking.rb
.

Finished in 0.00088 seconds
1 example, 0 failures