locations.rake

task :default_cities => :environment do
  require 'fastercsv'

  city_map = City.all.inject({}) do |cities, city|
    cities[city.name] ||= []
    cities[city.name] << city
    cities
  end

  population = {}

  FasterCSV.open('population.csv','r').each do |r|
    name = r[0].strip
    title = name + ', '+r[1].strip
    population[title] = r[2].gsub(',','').to_i
  end

  defaults = []

  city_map.reject{|name, c| c.length==1}.each do |name, cities|
    max = 0
    next_max = 0
    max_city = nil
    cities.each do |city|
      p = population[city.title]
      if !p.nil? && p>max
        next_max = max
        max = p
        max_city = city
      end
    end
    if max_city && (max>40000) && (next_max==0 || (max/next_max>9))
      defaults << max_city
    end
  end

  puts defaults.map(&:title).sort.join("\n")
end