[Rd] paste(character(0), collapse="", recycle0=FALSE) should be ""

[William Dunlap]

I agree: paste(collapse="something", ...) should always return a single
character string, regardless of the value of recycle0.  This would be
similar to when there are no non-NULL arguments to paste; collapse="."
gives a single empty string and collapse=NULL gives a zero long character
vector.
> paste()
character(0)
> paste(collapse=", ")
[1] ""

Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Thu, Apr 30, 2020 at 9:56 PM suharto_anggono--- via R-devel <
r-devel using r-project.org> wrote:

> Without 'collapse', 'paste' pastes (concatenates) its arguments
> elementwise (separated by 'sep', " " by default). New in R devel and R
> patched, specifying recycle0 = FALSE makes mixing zero-length and
> nonzero-length arguments results in length zero. The result of paste(n,
> "th", sep = "", recycle0 = FALSE) always have the same length as 'n'.
> Previously, the result is still as long as the longest argument, with the
> zero-length argument like "". If all og the arguments have length zero,
> 'recycle0' doesn't matter.
>
> As far as I understand, 'paste' with 'collapse' as a character string is
> supposed to put together elements of a vector into a single character
> string. I think 'recycle0' shouldn't change it.
>
> In current R devel and R patched, paste(character(0), collapse = "",
> recycle0 = FALSE) is character(0). I think it should be "", like
> paste(character(0), collapse="").
>
> paste(c("4", "5"), "th", sep = "", collapse = ", ", recycle0 = FALSE)
> is
> "4th, 5th".
> paste(c("4"     ), "th", sep = "", collapse = ", ", recycle0 = FALSE)
> is
> "4th".
> I think
> paste(c(        ), "th", sep = "", collapse = ", ", recycle0 = FALSE)
> should be
> "",
> not character(0).
>
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