rep {base}R Documentation

Replicate Elements of Vectors and Lists


rep replicates the values in x. It is a generic function, and the default method is described here. is a faster simplified version for the commonest case.


rep(x, times, ...)

## Default S3 method:
rep(x, times, length.out, each, ...), times)


x a vector (of any mode including a list) or a pairlist or a POSIXct or POSIXlt or date object.
times optional non-negative integer. A vector giving the number of times to repeat each element if of length length(x), or to repeat the whole vector if of length 1.
length.out optional integer. The desired length of the output vector.
each optional integer. Each element of x is repeated each times.
... further arguments to be passed to or from other methods.


A least one of times, length.out and each must be specified, and normally exactly one is. If length.out is given, times is ignored. If each is specified with either of the other two, its replication is performed first, and then that implied by times or length.out.

If times consists of a single integer, the result consists of the values in x repeated this many times. If times is a vector of the same length as x, the result consists of x[1] repeated times[1] times, x[2] repeated times[2] times and so on.

length.out may be given in place of times, in which case x is repeated as many times as is necessary to create a vector of this length.

Non-integer values of times will be truncated towards zero. If times is a computed quantity it is prudent to add a small fuzz.

If x has length zero and length.out is supplied and is positive, the values are filled in using the extraction rules, that is by an NA of the appropriate class for an atomic vector (0 for raw vectors) and NULL for a list.


A vector of the same class as x.


If the original vector has names, these are also replicated and so will almost always contain duplicates. (In contrast, S strips the names.)

Function is a simple case handled by internal code, and provided as a separate function purely for S compatibility.


Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

seq, sequence.


rep(1:4, 2)
rep(1:4, each = 2)       # not the same.
rep(1:4, c(2,2,2,2))     # same as second.
rep(1:4, c(2,1,2,1))
rep(1:4, each = 2, len = 4)    # first 4 only.
rep(1:4, each = 2, len = 10)   # 8 integers plus two recycled 1's.
rep(1:4, each = 2, times = 3)  # length 24, 3 complete replications

rep(1, 40*(1-.8)) # length 7 on most platforms
rep(1, 40*(1-.8)+1e-7) # better

## replicate a list
fred <- list(happy = 1:10, name = "squash")
rep(fred, 5)

# date-time objects
x <- .leap.seconds[1:3]
rep(x, 2)
rep(as.POSIXlt(x), rep(2, 3))

[Package base version 2.1.0 Index]