Accord.Statistics.Tools.Rank C# (CSharp) Method

        public static double[] Rank(this double[] samples, bool alreadySorted = false)
        {
            int[] idx = Vector.Range(0, samples.Length);

            if (!alreadySorted)
            {
                samples = (double[])samples.Clone();
                Array.Sort(samples, idx);
            }

            double[] ranks = new double[samples.Length];

            double tieSum = 0;
            int tieSize = 0;

            int start = 0;
            while (samples[start] == 0) start++;

            ranks[start] = 1;
            for (int i = start + 1, r = 1; i < ranks.Length; i++)
            {
                // Check if we have a tie
                if (samples[i] != samples[i - 1])
                {
                    // This is not a tie.
                    // Was a tie before?
                    if (tieSize > 0)
                    {
                        // Yes. Then set the previous
                        // elements with the average.

                        for (int j = 0; j < tieSize + 1; j++)
                            ranks[i - j - 1] = (r + tieSum) / (tieSize + 1);

                        tieSize = 0;
                        tieSum = 0;
                    }

                    ranks[i] = ++r;
                }
                else
                {
                    // This is a tie. Compute how 
                    // long we have been in a tie.
                    tieSize++;
                    tieSum += r++;
                }
            }

            if (!alreadySorted)
                Array.Sort(idx, ranks);

            return ranks;
        }

        public void RankTest1()
        {
            double[] values = { 2, 3, 4, 4, 5, 6, 8, 10, 10, 14, 16, 20, 32, 40 };

            double[] expected = { 1, 2, 3.5, 3.5, 5, 6, 7, 8.5, 8.5, 10, 11, 12, 13, 14 };
            double[] actual   = Tools.Rank(values);

            Assert.IsTrue(expected.IsEqual(actual));
        }