Statistics.cs

 public static class Statistics
    {
        public static double StreamAverage(double previousAverage, double currentNumber, double currentCount)
        {
            return ((previousAverage*currentCount) + currentNumber)/(currentCount + 1);
        }                    

        public static double Entropy<T>(this IDictionary<T, int> histogram, int dataSize)
        {
            double entropy = 0;
            foreach (KeyValuePair<T, int> numberCount in histogram)
            {
                double probability = (double)numberCount.Value / dataSize;
                entropy += probability * Math.Log(1 / probability, 2);
            }
            return entropy;
        }
    }