How to get 4 closest to “a” elements from the list of tuples in C#?

Question

I have a list of tuples List<(double X, double Y)> Data and a variable of type double . It is required to add to the array (double, double)[] output the 4 elements closest to a . They need to be found among all Data.X . It is necessary to arrange data in order of distance from a .

Example:

Input:

a = 15.5;

{(-10, 1),

(12, 2),

(14, 3),

(16, 4),

(50, 5)}

Output:

output [0] = (16, 4);
output [1] = (14, 3);
output [2] = (12, 2);
output [3] = (-10, 1);

EDIT:My current solution:

class CubicSpline
    {
        List<(double X, double Y)> Data { get; set; }
        public CubicSpline(List<(double X, double Y)> data)
        {
            Data = data;
        }

        /// <summary>
        /// Method for finding 4 nearest neighbors for x.
        /// </summary>
        public (double, double)[] FindNeighbours(double x)
        {
            var temp = Data.OrderBy(b => Math.Abs(x - b.X)).ToList();
            (double, double)[] output = new (double, double)[4];
            for(int i = 0; i < 4; i++)
            {
                output[i] = temp[i];
            }
            return output;
        }
    }

Answer 1

Since you started with LINQ, you can use some other LINQ methods to compute the result:

public (double, double)[] FindNeighbours(double x) =>
    Data.OrderBy(b => Math.Abs(x - b.X)).Take(4).ToArray();