Hi All, I have the following adjacency matrix for a directed graph:
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [1,] 0 0 0 0 0 0 0 0 [2,] 0 0 0 0 0 0 0 0 [3,] 1 0 0 0 0 0 0 0 [4,] 0 0 1 0 0 0 0 0 [5,] 0 0 1 0 0 0 0 0 [6,] 1 1 0 0 0 0 0 0 [7,] 0 0 0 1 1 0 0 0 [8,] 0 0 0 0 0 1 1 0 My interest is the numberof path between (8) and (1). Using a standard matrix moltiplication I can see I have one pathe of length 2 and two paths of length 4. (paths of length 2) [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [1,] 0 0 0 0 0 0 0 0 [2,] 0 0 0 0 0 0 0 0 [3,] 0 0 0 0 0 0 0 0 [4,] 1 0 0 0 0 0 0 0 [5,] 1 0 0 0 0 0 0 0 [6,] 0 0 0 0 0 0 0 0 [7,] 0 0 2 0 0 0 0 0 [8,] 1 1 0 1 1 0 0 0 (paths of length 4) [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [1,] 0 0 0 0 0 0 0 0 [2,] 0 0 0 0 0 0 0 0 [3,] 0 0 0 0 0 0 0 0 [4,] 0 0 0 0 0 0 0 0 [5,] 0 0 0 0 0 0 0 0 [6,] 0 0 0 0 0 0 0 0 [7,] 0 0 0 0 0 0 0 0 [8,] 2 0 0 0 0 0 0 0 All in all I have 3 paths (not all of the same length) between (8) and (1). Is there already a function in R (whatever the library) that will list the nodes touched in all those three paths (i.e. 8 -> 6 -> 1; 8 - > 7 -> 4 -> 3 -> 1; 8 -> 7 -> 5 -> 3 -> 1)? Regards, Federico Calboli -- Federico C. F. Calboli Department of Epidemiology and Public Health Imperial College, St. Mary's Campus Norfolk Place, London W2 1PG Tel +44 (0)20 75941602 Fax +44 (0)20 75943193 f.calboli [.a.t] imperial.ac.uk f.calboli [.a.t] gmail.com ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html