Example 2: Sorting

The rows of a 10 x 3 matrix x are sorted in ascending order using Columns 0 and 1 as the keys. There are two missing values (NaNs) in the keys. The observations containing these values are moved to the end of the sorted array.

using System;
using Imsl.Math;
using Imsl.Stat;

public class SortEx2
{
    public static void  Main(String[] args)
    {
        int nKeys = 2;
        double[,] x = {
            {1.0, 1.0, 1.0}, {2.0, 1.0, 2.0},
            {1.0, 1.0, 3.0}, {1.0, 1.0, 4.0},
            {2.0, 2.0, 5.0}, {1.0, 2.0, 6.0},
            {1.0, 2.0, 7.0}, {1.0, 1.0, 8.0},
            {2.0, 2.0, 9.0}, {1.0, 1.0, 9.0}
        };
        
        int[] iperm = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
        x[4,1] = Double.NaN;
        x[6,0] = Double.NaN;
        
        PrintMatrix pm = new PrintMatrix("The Input Array");
        PrintMatrixFormat mf = new PrintMatrixFormat();
        mf.SetNoRowLabels();
        mf.SetNoColumnLabels();
        //    Print the array
        pm.Print(mf, x);
        Console.Out.WriteLine();
        
        Sort.Ascending(x, nKeys, iperm);
        
        pm = new PrintMatrix("The Sorted Array - Lowest to Highest");
        mf = new PrintMatrixFormat();
        mf.SetNoRowLabels();
        mf.SetNoColumnLabels();
        
        //    Print the array
        pm.Print(mf, x);
        
        pm = new PrintMatrix("The permutation array");
        mf = new PrintMatrixFormat();
        mf.SetNoRowLabels();
        mf.SetNoColumnLabels();
        pm.Print(mf, iperm);
    }
}

Output

The Input Array
               
1    1    1  
2    1    2  
1    1    3  
1    1    4  
2    NaN  5  
1    2    6  
NaN  2    7  
1    1    8  
2    2    9  
1    1    9  


The Sorted Array - Lowest to Highest
               
1    1    1  
1    1    3  
1    1    4  
1    1    8  
1    1    9  
1    2    6  
2    1    2  
2    2    9  
2    NaN  5  
NaN  2    7  

The permutation array
     
0  
2  
3  
7  
9  
5  
1  
8  
4  
6