numl.Math.LinearAlgebra.Matrix.GetCols C# (CSharp) Method

        public IEnumerable<Vector> GetCols()
        {
            for (int i = 0; i < Cols; i++)
                yield return this[i, VectorType.Col];
        }

        /// <summary>
        /// Sorts the given Matrix by the specified row or column selector and returns the new Matrix
        /// along with the original indices.
        /// </summary>
        /// <param name="source">The Matrix</param>
        /// <param name="keySelector">Property selector to sort by.</param>
        /// <param name="t">Specifies whether to sort horizontally or vertically.</param>
        /// <param name="ascending">Determines whether to sort ascending or descending (Default: True)</param>
        /// <param name="indices">Vector of <paramref name="t"/> indices in the original Matrix before the sort operation.</param>
        /// <returns>New Matrix and Vector of original indices.</returns>
        public static Matrix Sort(Matrix source, Func <Vector, double> keySelector, VectorType t, bool ascending, out Vector indices)
        {
            int max = (t == VectorType.Row ? source.Rows : source.Cols);

            indices = Vector.Zeros(max);

            List <Vector> vects = new List <Vector>(max);

            IEnumerable <Vector> arrays = (t == VectorType.Row ? source.GetRows() : source.GetCols());

            KeyValuePair <Vector, int>[] sort = (ascending ?
                                                 arrays.Select((i, v) => new KeyValuePair <Vector, int>(i, v))
                                                 .OrderBy(o => keySelector(o.Key))
                                                                                                                 :
                                                 arrays.Select((i, v) => new KeyValuePair <Vector, int>(i, v))
                                                 .OrderByDescending(o => keySelector(o.Key))).ToArray();

            indices = sort.Select(s => s.Value).ToVector();

            return(sort.Select(s => s.Key).ToMatrix(t));
        }