# A quick way to do row repeat and col repeat (rep.row, rep.col)

**R HEAD**, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here)

Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

Today I worked on a simulation program which require me to create a matrix by repeating the vector n times (both by row and by col).

Even the task is extremely simple and only take 1 line to finish(10sec), I have to think about should the argument in rep be each or times and should the argument in matrix is nrow or ncol. It distracted me from the original task i am working on.

Just now, I wrote a function rep.row and rep.col to do what I really want to do. Next time, i don’t have to worry about how to use the matrix and rep command to repeat an vector to form a matrix!

Code

rep.row<-function(x,n){ matrix(rep(x,each=n),nrow=n) } rep.col<-function(x,n){ matrix(rep(x,each=n), ncol=n, byrow=TRUE) }

x is the vector to be repeated and n is the number of replication. Example:

> rep.row(1:3,5) [,1] [,2] [,3] [1,] 1 2 3 [2,] 1 2 3 [3,] 1 2 3 [4,] 1 2 3 [5,] 1 2 3 > rep.col(1:3,5) [,1] [,2] [,3] [,4] [,5] [1,] 1 1 2 2 3 [2,] 1 1 2 3 3 [3,] 1 2 2 3 3

I am sure it should appear in some packages, but it would be faster for me to write it out than find it out!

**leave a comment**for the author, please follow the link and comment on their blog:

**R HEAD**.

R-bloggers.com offers

**daily e-mail updates**about R news and tutorials about learning R and many other topics. Click here if you're looking to post or find an R/data-science job.

Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.