Contents

class Array
  def weighted_sample(weights=nil)
    weights = Array.new(length, 1.0) if weights.nil? || weights.sum == 0
    total = weights.sum

    # The total sum of weights is multiplied by a random number
    trigger = Kernel::rand * total

    subtotal = 0
    result = nil

    # The subtotal is checked agains the trigger. The higher the sum, the higher
    # the probability of triggering a result.
    weights.each_with_index do |weight, index|
      subtotal += weight

      if subtotal > trigger
        result = self[index]
        break
      end
    end
    # Returns self.last from current array if result is nil
    result || last
  end
end

Version data entries

9 entries across 9 versions & 1 rubygems

Version	Path
ab_panel-0.4.4	lib/array.rb
ab_panel-0.4.3	lib/array.rb
ab_panel-0.4.2	lib/array.rb
ab_panel-0.4.1	lib/array.rb
ab_panel-0.4.0	lib/array.rb
ab_panel-0.3.3	lib/array.rb
ab_panel-0.3.2	lib/array.rb
ab_panel-0.3.1	lib/array.rb
ab_panel-0.3.0	lib/array.rb