randomDistribution.frink


use binarySearch.frink

// This class generates random elements from a discrete set with a
// known distribution, for example, the frequency of letters in the English
// language.
class randomDistribution
{
   // An array of elements
   var elements

   // The sum of probabilities
   var sum
   
   new[] :=
   {
      elements = new array
      sum = 0
   }

   // Adds an item with the specified probability.
   add[item, prob] :=
   {
      sum = sum + prob
      elements.push[ [item, prob, sum] ]
   }

   // Selects a random item based on the specified probabilities.
   random[] :=
   {
      z = randomFloat[0, sum]
      index = binarySearch[elements, z, {|a,b| a <=> b@2}]
      return elements@index@0
   }
}


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This is a program written in the programming language Frink.
For more information, view the Frink Documentation or see More Sample Frink Programs.

Alan Eliasen was born 14705 days, 19 hours, 54 minutes ago.