sorting variable multidimensional arrays

Question

I have the array of integers: d[]. for example(7 columns and some rows):

4 1 8 0 3 2 6

7 0 4 9 1 1 5

0 6 1 3 5 2 0

and so on. At compile time I do not know how many columns has array d. And I do not know at compile time which columns to use to orderby.

For example need to sort by: d[5], d[2], d[0], d[3]. But at run time I know order of the columns to sort. For example column indexes: 5, 2, 0, 3 which mean d[5], d[2], d[0], d[3] columns. How can I orderby array d using this indexes of columns?

Answer 1

I suggest using DataTable to create a column structure at runtime & adding rows. And then sort it using Column's name.

e.g. DataTable.Sort = "Column5 ASC, Column2 ASC" (pseudocode).

Answer 2

Assuming you are using a jagged array (int[][]), then you can use LINQ by combining OrderBy and ThenBy:

using System;
using System.Collections.Generic;
using System.Linq;
static class Program
{
    static void Main()
    {
        int[][] data = {
          new[]{4,1,8,0,3,2,6},
          new[]{7,0,4,9,1,1,5},
          new[]{0,6,1,3,5,2,0}};
        int[] sortCols = { 5, 2, 0, 3 };

        IEnumerable<int[]> qry = data;
        if (sortCols.Length > 0)
        {
            IOrderedEnumerable<int[]> sorted =
                qry.OrderBy(row => row[sortCols[0]]);
            for (int i = 1; i < sortCols.Length; i++)
            {
                int col = sortCols[i]; // for capture
                sorted = sorted.ThenBy(row => row[col]);
            }
            qry = sorted;
        }

        // show results (does actual sort when we enumerate)
        foreach (int[] row in qry)
        {
            foreach (int cell in row)
            {
                Console.Write(cell);
                Console.Write('\t');
            }
            Console.WriteLine();
        }
    }
}

You could also (alternatively) build a comparison to pass to Array.Sort.