Dear R experts, Suppose I have a matrix A below.
a <- rep(1:4, each=5) b <- rep(1:5, 4) c <- rnorm(20) A <- cbind(a,b,c) > A a b c [1,] 1 1 0.761806718 [2,] 1 2 0.239734573 [3,] 1 3 -0.728339238 [4,] 1 4 -0.121946174 [5,] 1 5 -0.131909077 [6,] 2 1 -0.069790098 [7,] 2 2 1.082671767 [8,] 2 3 -0.869537195 [9,] 2 4 -0.417222758 [10,] 2 5 -2.432273481 [11,] 3 1 0.425432121 [12,] 3 2 -2.453299938 [13,] 3 3 0.612125174 [14,] 3 4 -0.005387462 [15,] 3 5 1.911146222 [16,] 4 1 0.161408685 [17,] 4 2 0.567118882 [18,] 4 3 -0.948882839 [19,] 4 4 0.485002340 [20,] 4 5 -0.551981333 With this matrix A, I'd like to create several sub-matrices, for example B <- subset(A, (A[,1] %in% c(1,2) & A[,2] %in% c(1,2)) | (A[,1] %in% c(3) & A[,2] %in% c(1) ) | (A[,1] %in% c(4) & A[,2] %in% c(1:4)) ) > B a b c [1,] 1 1 0.7618067 [2,] 1 2 0.2397346 [3,] 2 1 -0.0697901 [4,] 2 2 1.0826718 [5,] 3 1 0.4254321 [6,] 4 1 0.1614087 [7,] 4 2 0.5671189 [8,] 4 3 -0.9488828 [9,] 4 4 0.4850023 or C <- subset(A, (A[,1] %in% c(1:4) & A[,2] %in% c(1,2)) ) > C a b c [1,] 1 1 0.7618067 [2,] 1 2 0.2397346 [3,] 2 1 -0.0697901 [4,] 2 2 1.0826718 [5,] 3 1 0.4254321 [6,] 3 2 -2.4532999 [7,] 4 1 0.1614087 [8,] 4 2 0.5671189 or D <- subset(A, (A[,1] %in% c(1,2) & A[,2] %in% c(1:3)) | (A[,1] %in% c(3) & A[,2] %in% c(1,2)) ) > D a b c [1,] 1 1 0.7618067 [2,] 1 2 0.2397346 [3,] 1 3 -0.7283392 [4,] 2 1 -0.0697901 [5,] 2 2 1.0826718 [6,] 2 3 -0.8695372 [7,] 3 1 0.4254321 [8,] 3 2 -2.4532999 and so forth. I am wondering if I could create matrices B, C, D etc AT ONE TIME. In order to do that, I guess I need to make a "function". unfortunately, I have no idea how to do that. Any suggestion will be greatly appreciated. Kathryn Lord [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.