Testing Harmonia's fairness algorithm

output

{"blog"=>{"Alice"=>2422, "Bob"=>2542, "Clare"=>2503, "Dave"=>2533},
 "invoice"=>{"Alice"=>2504, "Bob"=>2493, "Clare"=>2535, "Dave"=>2468},
 "fire_log"=>{"Alice"=>2488, "Bob"=>2500, "Clare"=>2479, "Dave"=>2533}}

test.rb

require "pp"

# The essential algorithm from Harmonia

def random_available_person_for(task)
  task_counts = @people.inject({}) do |h, person|
    h[person] = assigned_tasks_ignoring(task, person).count
    h
  end

  @people.select { |person| task_counts[person] == task_counts.values.min }.shuffle.first
end

def assigned_tasks_ignoring(task, person)
  # This has been slightly modified for simplicity
  @assignments[person] - [task]
end


# ... now to run it.

@people = %w(Alice Bob Clare Dave)
@tasks = %w(blog invoice fire_log)

base_stats = @people.inject({}) { |h,p| h[p] = 0; h }
statistics = {}
@tasks.each do |task|
  statistics[task] = base_stats.dup
end

10000.times do
  @assignments = Hash.new { [] }

  @tasks.each do |task|
    person = random_available_person_for(task)
    @assignments[person] << task
    statistics[task][person] += 1
  end
end

pp statistics