A Ruby library for ranking scorable types using various ranking strategies.
Ranker is tested against MRI (1.8.7+) and JRuby (1.9.0+).
With bundler, add the ranker gem to your Gemfile.
gem "ranker"Require the ranker gem in your application.
require "ranker"Default ranking will assume values are numeric and rank them in their natural sorting (ascending) order. For example, a score of 100 is higher than a score of 50.
scores = [1, 1, 2, 3, 3, 1, 4, 4, 5, 6, 8, 1, 0, 8]
rankings = Ranker.rank(scores)
rankings.count #=> 8
ranking = rankings[0]
ranking.rank #=> 1
ranking.score #=> 8
ranking.rankables #=> [8, 8]
ranking.percentile #=> 100
ranking.z_score #=> 1.83921346366645Custom ranking allows for ranking of objects by using a symbol or a lambda.
class Player
attr_accesor :score
def initalize(score)
@score = score
end
end
players = [Player.new(0), Player.new(100), Player.new(1000), Player.new(25)]
rankings = Ranker.rank(players, :by => lambda { |player| player.score })
# or
rankings = Ranker.rank(players, :by => :score)In some cases objects need to be ranked by score in descending order, for example, if you were ranking golf players. In this case a score of 75 is higher than a score of 100.
class GolfPlayer < Player
end
players = [GolfPlayer.new(72), GolfPlayer.new(100), GolfPlayer.new(138), GolfPlayer.new(54)]
rankings = Ranker.rank(players, :by => :score, :asc => false)Ranker has a number of ranking strategies available to use, mostly based on the Wikipedia entry on ranking. Strategies can be passed in as an option to the rank method.
rankings = Ranker.rank(players, :by => :score, :strategy => :ordinal)This is the default ranking strategy. For more info, see the Wikipedia entry on Standard Competition Ranking.
rankings = Ranker.rank(players, :by => :score, :strategy => :standard_competition)For more info, see the Wikipedia entry on Modified Competition Ranking.
rankings = Ranker.rank(players, :by => :score, :strategy => :modified_competition)For more info, see the Wikipedia entry on Dense Ranking.
rankings = Ranker.rank(players, :by => :score, :strategy => :dense)For more info, see the Wikipedia entry on Ordinal Ranking.
rankings = Ranker.rank(players, :by => :score, :strategy => :ordinal)If you find the current strategies not to your liking, you can write your own and pass the class into the rank method.
class MyCustomStrategy < Ranker::Strategies::Strategy
def execute
# My code here
end
end
rankings = Ranker.rank(players, :by => :score, :strategy => MyCustomStrategy)Copyright © 2013 Ilya Scharrenbroich. Released under the MIT License.