How to know all rows of which column in matrix has data?

Question

Hi
I have a matrix, I want to know which rows of first column has data , and if first row has data I check the other columns to have a data.

m= 1 0 0 1
0 1 1 0
1 1 1 0
in this matrix, the first column has 2 data, first and third rows. At this time I see the other column in frist row and I get that third column has data, I compute Jaccard similarity for first and third rows

Vulpes · Answer

OK, try this then: using System; using System.Collections.Generic; using System.Linq; class Program { static void Main() { int[,] m = new int[3, 4]{{1, 0, 0, 1}, {0, 1, 1, 0}, {1, 1, 1, 0}}; var rows = new List (); // find which rows have a first column containing a non-zero value for(int i = 0; i { if(m[i,0] != 0) rows.Add(i); } if (rows.Count == 2) { Console.WriteLine("The following rows have data in the first column
"); PrintRow(m, rows[0]); PrintRow(m, rows[1]); Console.WriteLine("The Jaccard similarity coeffcient is {0}",Jaccard(m, rows[0], rows[1])); } Console.ReadKey(); } static double Jaccard(int[,] m, int r1, int r2) { int[] a = new int[m.GetLength(1)]; int[] b = new int[m.GetLength(1)]; for(int j = 0; j { a[j] = m[r1, j]; b[j] = m[r2, j]; } return (double)a.Intersect(b).Count()/a.Union(b).Count(); } static void PrintRow(int[,] m, int r) { Console.Write("("); for(int j = 0; j { Console.Write(m[r,j]); if (j } Console.WriteLine(")"); } }

diamond diamond · Answer

I appreciated you for your response. But my matrix is created as below, I save src IP addresses in every time window, rows are src Ip address and columns are time window. int[,] Failure_matrix = new int[5, size]; I want to know which src ip addresses are seen in current time window(be 1 in matrix), it is saved in first column of matrix. my Jaccard similarity is different from what is you have written, I want acquire intersect of src ip address are 1 in current time window with other time windows (columns). I mean, if I see one src ip is 1 in current time window, I see the others time windows that this src ip was 1 and other src ipadddres that time window are 1, then I compute their union and intersect by Jaccard

Vulpes · Answer

I only followed some of that but the following may help you to figure out what you need. I've only dealt with the case where 2 rows contains data in the first column as I wasn't sure what to do in other scenarios. Note that it's convenient here to express the matrix as a jagged array even though the lengths of all the rows are, of course, the same. This is because one can easily extract a whole row from the jagged array: using System; using System.Linq; class Program { static void Main() { int[][] m = new int[3][]; m[0] = new int[]{1, 0, 0, 1}; m[1] = new int[]{0, 1, 1, 0}; m[2] = new int[]{1, 1, 1, 0}; // find which rows have a first column containing 1 int[][] rows = m.Where(e => e[0] == 1).ToArray(); if (rows.Length == 2) { Console.WriteLine("The following rows have data in the first column
"); PrintRow(rows[0]); PrintRow(rows[1]); Console.WriteLine("The Jaccard similarity coeffcient is {0}",Jaccard(rows[0], rows[1])); } Console.ReadKey(); } static double Jaccard(int[] a, int[] b) { int m11 = 0; int m01 = 0; int m10 = 0; for (int i = 0; i { if (a[i] == 1 && b[i] == 1) m11++; else if (a[i] == 0 && b[i] == 1) m01++; else if(a[i] == 1 && b[i] == 0) m10++; } return (double)m11/(m01 + m10 + m11); } static void PrintRow(int[] a) { Console.Write("("); for(int i = 0; i { Console.Write(a[i]); if (i } Console.WriteLine(")"); } }