Create sequence of repeated values, in sequence?

Question

I need a sequence of repeated numbers, i.e. 1 1 ... 1 2 2 ... 2 3 3 ... 3 etc. The way I implemented this was:

  nyear <- 20   names <- c(rep(1,nyear),rep(2,nyear),rep(3,nyear),rep(4,nyear),              rep(5,nyear),rep(6,nyear),rep(7,nyear),rep(8,nyear)) 

which works, but is clumsy, and obviously doesn't scale well.

How do I repeat the N integers M times each in sequence?

• I tried nesting seq() and rep() but that didn't quite do what I wanted.
• I can obviously write a for-loop to do this, but there should be an intrinsic way to do this!

Answer 1

You missed the each= argument to rep():

R> n <- 3 R> rep(1:5, each=n)  [1] 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 R>  

so your example can be done with a simple

R> rep(1:8, each=20) 

Answer 2

Another base R option could be gl():

gl(5, 3) 

Where the output is a factor:

 [1] 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 Levels: 1 2 3 4 5 

If integers are needed, you can convert it:

as.numeric(gl(5, 3))   [1] 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5