Drop table calculator

dice.rb

class Item
  attr_accessor :name, :odds

  def initialize(name, odds)
    @name = name
    @odds = odds
  end
end

class Dice
  def initialize(items)
    @range = 10000
    i = 0
    # @items = items.map do |item|
    #   lower = i
    #   i += item.odds * @range
    #   upper = i
    #   { :item => item, :lower_bound => lower, :upper_bound => upper}
    # end
    @items = []
    for item in items do
      lower = i
      i += item.odds * @range
      upper = i
      @items << { :item => item, :lower_bound => lower, :upper_bound => upper}
    end
  end

  def spin
    spun = rand(@range)
    # result = @items.select do |item|
    #   spun >= item[:lower_bound] && spun < item[:upper_bound]
    # end
    result = []
    for item in @items do
      if spun >= item[:lower_bound] && spun < item[:upper_bound]
        result << item
      end
    end
    result.empty? ? nil : result.first[:item]
  end
end


dice = Dice.new [
  Item.new("Gear", 0.25),
  Item.new("Enemy", 0.15),
  Item.new("Tree", 0.20),
  Item.new("Shield", 0.01),
  Item.new("Oil", 0.05),
  Item.new("Gold", 0.005),
  Item.new("Cone", 0.05)
]

# Now testing it

spins = []
cycles = 100000

cycles.times do
  weee = dice.spin
  spins << (weee.nil? ? "Nothing" : weee.name)
end

results = spins.group_by { |s| s }
results.each do |name, entries|
  count = entries.count
  puts "#{name}\t\t#{count}\t#{1.0*count/cycles*100.00}%"
end

# name    count %
# ----    ----  ----
# Enemy   14935 14.935%
# Nothing 28490 28.49%
# Cone    4948  4.948%
# Tree    19914 19.914%
# Shield  1068  1.068%
# Gear    25080 25.080000000000002%
# Oil     5079  5.079000000000001%
# Gold    486   0.486%