Putting rows as a single column in r

Something like this?

X <- matrix(letters[1:9], ncol=3)
matrix(X, ncol=1)

R matrices are in column major order, so you can easily concatenate them into a single column vector with the matrix function.

I find stack also very useful

X <- data.frame(matrix(letters[1:9], ncol=3),stringsAsFactors=FALSE)
stack(X)[,"values",drop=FALSE]