Class: Array

Inherits:
Object
  • Object
show all
Defined in:
lib/array.rb

Instance Method Summary collapse

Instance Method Details

#weighted_sample(weights = nil) ⇒ Object 



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# File 'lib/array.rb', line 2

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