Second minimum of two dimensional array

Question

I want to get the second minimum value of a two dimensional array, my original Array contains a lot of zeros which i can't do anything about them but i want to get the minimum value that's why i thought about this idea, anyone has a clue ? i tried the following order for the lowest value which works. the code i just put it to be ale to post the question and i don't need it to be modified i just want to know how can i get the second minimum value.

low1 = result1.Cast().Min();

        for (int m = 0; m < Weights.Count; m++)
        {
            int offset = m * ListCranelocations.Count;

            for (int i = 0; i < ListCranelocations.Count; i++)
            {
                for (int j = 0; j < ListPickLocations.Count; j++)
                {
                    double x = ListCranelocations[i].Lat - ListPickLocations[j].Lat;
                    double y = ListCranelocations[i].Lng - ListPickLocations[j].Lng;
                    R1[i] = Math.Sqrt(Math.Pow(x, 2) + Math.Pow(y, 2));

                    if ( R1[i] > Clearance )
                    {     
                        result1[i + offset, j] = Weights[m] * R1[i];

                         //Console.WriteLine(result1[i, j]);
                    } 

                }
            }
        }


        for (int m = 0; m < Weights.Count; m++)

        {
            int offset = m * ListCranelocations.Count;

            for (int i = 0; i < ListCranelocations.Count; i++)
            {
                for (int j = 0; j < ListSetlocations.Count; j++)
                {

                    double x = ListCranelocations[i].Lat - ListSetlocations[j].Lat;
                    double y = ListCranelocations[i].Lng - ListSetlocations[j].Lng;
                    R2[i] = Math.Sqrt(Math.Pow(x, 2) + Math.Pow(y, 2));

                    if (R2[i] > Clearance )
                    {

                        result2[i + offset, j] = Weights[m] * R2[i];

                        //  Console.WriteLine(result2[i, j]);
                    }


                }

            }
        }

        double low = 0;
        double low1 = 0;
        double low2 = 0;
        double low23 = 0;


        for (int i = 0; i < result1.GetLength(0); i++)
        {
            for (int j = 0; j < result1.GetLength(1); j++)
            {
                for (int k = 0; k < result2.GetLength(0); k++)
                {
                    for (int m = 0; m < result2.GetLength(1); m++)
                    {

                        if (!(result1[i, j] == 0) && !(result2[k, m] == 0))
                        {

                            result3[i, j] = result1[i, j] + "," + result2[k, m];


                            // Console.WriteLine(result3[i, j]);
                          /*  
                            if ((result1[i, j]) > (result2[k, m]))
                            {
                                highestMoment[i, j] = result1[i, j];
                            }
                            else
                            {
                                highestMoment[i, j] = result2[k, m];
                            }
                            */



                            low1 = result1.Cast<double>().Min();
                            low2 = result2.Cast<double>().Min();

                            if (low1 > low2)
                            {
                                low = low1;
                                Index[i, j] = "P";
                            }
                            else if (low1 > low2)
                            {
                                low = low2;
                                Index[i, j] = "S";
                            }

                            counter++;


                        }


                          // Console.WriteLine(highestMoment[i, j]);



                    }
                }

            }

        }

Something like `var twoLowest = result1.OrderBy(x => x).Take(2).ToList()`? — Olivier Jacot-Descombes, May 03 '19 at 21:49

Rufus L · Answer 1 · 2019-05-03T22:03:33.283

You can use Linq extension methods to get what you need pretty easily. As you already know, you can call Cast<double> to get all the items into an IEnumerable<double>, so now you can follow up with Distinct, which gets all the unique numbers, then OrderBy(i => i) to sort the results, and finally you can use Skip to skip the first value and then FirstOrDefault to get the first value after that (so the second-to-smallest number):

double secondSmallestValue = twoDimensionalArrayOfValues
    .Cast<double>()
    .Distinct()
    .OrderBy(i => i)
    .Skip(1)
    .FirstOrDefault();

If you prefer the for loop approach for any reason, you can accomplish something similar by keeping track of the smallest and second-smallest values, and then walking through each item in the array to see if you find one smaller than the current smallest. When you do, just set secondSmallest = smallest and smallest = currentValue:

var smallestValue = int.MaxValue;
var secondSmallestValue = int.MaxValue;

for(int row = 0; row < values.GetUpperBound(0); row++)
{
    for (int col = 0; col < values.GetUpperBound(1); col++)
    {
        var thisValue = values[row, col];

        if (thisValue < smallestValue)
        {
            // Here you have row and col variables if you need to
            // keep track of the indexes at which the items were found
            secondSmallestValue = smallestValue;
            smallestValue = thisValue;
        }
        else if (thisValue < secondSmallestValue)
        {
            secondSmallestValue = thisValue;
        }
    }
}

In the code above, values is defined as a 10x10 array filled with random integers from 0 to 99:

int rowCount = 10;
int colCount = 10;
Random rnd = new Random();

int[,] values = new int[rowCount, colCount];

for(int row = 0; row < rowCount; row++)
    for (int col = 0; col < colCount; col++)
        values[row, col] = rnd.Next(0, 100);

Second minimum of two dimensional array

1 Answers1