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

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 at 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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