Dear List, I am looking for a faster way of accomplishing this:
# n is an integer larger than two n <- 3 # matrix of 2^n binary outcomes bmat <- as.matrix(expand.grid( rep( list(1:0), n))[, n:1]) # I would like to know which rows of "bmat" have "1" in the "i" and "j" coordinates, so for n=3 in coordinates 1-2, 1- 3, and 2-3 # I would like then to construct "choose( n, 2)" binary vectors of lengths 2^n to indicate those rows with a "1" # The loop below accomplishes this task. Is there a faster way of doing the same? library(combinat) # matrix of all pairwise combinations cmat<-combn( n, 2) temp<-matrix(NA, nrow(bmat), ncol(cmat)) for (i in 1:nrow(bmat)) { for (j in 1:ncol(cmat)) { temp[ i, j]<-as.numeric( bmat[i,][cmat[1,j]] & bmat[i,][cmat[2,j]] == 1) } } Thank you very much for your help! Serguei Kaniovski ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code.