public static Tuple<double[][], Dictionary<int, uint>> ToCategorical(int[] data, uint numberOfClass, Dictionary<int, uint> classes = null)
        {
            double[][] categoricalArray = new double[data.Length][];
            if (classes == null)
                classes = new Dictionary<int, uint>();
            uint index = 0;
            for (int i = 0; i < data.Length; i++)
            {
                double[] row = new double[numberOfClass];
                if (!classes.ContainsKey(data[i]))
                {
                    classes.Add(data[i], index++);
                }
                row[classes[data[i]]] = 1f;
                categoricalArray[i] = row;
            }
            return Tuple.Create(categoricalArray, classes);
        }