Consider the following matrix nr <- nc <- 6 set.seed <- 123 m <- matrix(sample(c(rep(0,9), 1),nr*nc, replace=T), nrow=nr, ncol=nc) sum(m)/length(m) 0.1667 dimnames(m) <- list(letters, letters) m a b c d e f a 0 0 0 0 0 1 b 0 0 0 1 0 1 c 0 0 0 0 0 0 d 0 0 0 0 0 0 e 1 1 0 0 0 0 f 0...