The logic of passing a missing argument to the R-function rep

r

Solution

In the documentation, I see:

The default behaviour is as if the call was

rep(x, times = 1, length.out = NA, each = 1)

But it does not apply for `rep.int`, which requires times argument:

>rep(0,)
[1] 0

>rep.int(0,)
Error in rep.int(0, ) : argument "times" is missing, with no default

Problem

The following R function ``` tmp <- function(p) rep(0, length.out = p) ``` puzzles me, since ``` > tmp() [1] 0 ``` I would expect an error in the call, since `p` is missing. The documentation for `rep` says that Function 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. length.out. I don't understand the logic here. Why does `rep` seem to ignore that `p` is missing? R version 3.0.2 (2013-09-25)

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