rep replicates the values in
x. It is a generic function, and the (internal) default method is described here.
rep_len are faster simplified versions for two common cases. They are not generic.
rep(x, ...) rep.int(x, times) rep_len(x, length.out)
- a vector (of any mode including a list) or a factor or (for
Dateobject; or an S4 object containing such an object.
- further arguments to be passed to or from other methods. For the internal default method these can include:
- A integer vector giving the (non-negative) number of times to repeat each element if of length
length(x), or to repeat the whole vector if of length 1. Negative or
NAvalues are an error.
- non-negative integer. The desired length of the output vector. Other inputs will be coerced to an integer vector and the first element taken. Ignored if
- non-negative integer. Each element of
eachtimes. Other inputs will be coerced to an integer vector and the first element taken. Treated as
- non-negative integer: the desired length of the output vector.
The default behaviour is as if the call was
rep(x, times = 1, length.out = NA, each = 1)
. Normally just one of the additional arguments is specified, but if
each is specified with either of the other two, its replication is performed first, and then that implied by
times consists of a single integer, the result consists of the whole input repeated this many times. If
times is a vector of the same length as
x (after replication by
each), the result consists of
times 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. If both are given,
length.out takes priority and
times is ignored.
Non-integer values of
times will be truncated towards zero. If
times is a computed quantity it is prudent to add a small fuzz.
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 (
NULL for a list.
An object of the same type as
rep_len return no attributes (except the class if returning a factor).
The default method of
rep gives the result names (which will almost always contain duplicates) if
x had names, but retains no other attributes.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
rep.int is a simple case handled by internal code, and provided as a separate function partly for S compatibility and partly for speed (especially when names can be dropped).
rep is a primitive, but (partial) matching of argument names is performed as for normal functions. You can no longer pass a missing argument to e.g.
For historical reasons
rep works on
NULL: the result is always
NULL even when
length.out is positive.
Although it has never been documented, these functions have always worked on expression vectors. R 2.x.y accepted pairlists and some other objects (although the results were rarely what their users intended).
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)) ## named factor x <- factor(LETTERS[1:4]); names(x) <- letters[1:4] x rep(x, 2) rep(x, each = 2) rep.int(x, 2) # no names rep_len(x, 10)
Documentation reproduced from R 3.0.1. License: GPL-2.