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

[Hervé Pagès]

There is still the situation where **both** 'sep' and 'collapse' are 
specified:

   > paste(integer(0), "nth", sep="", collapse=",")
   [1] "nth"

In that case 'recycle0' should **not** be ignored i.e.

   paste(integer(0), "nth", sep="", collapse=",", recycle0=TRUE)

should return the empty string (and not character(0) like it does at the 
moment).

In other words, 'recycle0' should only control the first operation (the 
operation controlled by 'sep'). Which makes plenty of sense: the 1st 
operation is binary (or n-ary) while the collapse operation is unary. 
There is no concept of recycling in the context of unary operations.

H.

On 5/15/20 11:25, Gabriel Becker wrote:
> Hi all,
> 
> This makes sense to me, but I would think that recycle0 and collapse 
> should actually be incompatible and paste should throw an error if 
> recycle0 were TRUE and collapse were declared in the same call. I don't 
> think the value of recycle0 should be silently ignored if it is actively 
> specified.
> 
> ~G
> 
> On Fri, May 15, 2020 at 11:05 AM Hervé Pagès <hpages using fredhutch.org 
> <mailto:hpages using fredhutch.org>> wrote:
> 
>     Totally agree with that.
> 
>     H.
> 
>     On 5/15/20 10:34, William Dunlap via R-devel wrote:
>      > 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
>     <https://urldefense.proofpoint.com/v2/url?u=http-3A__tibco.com&d=DwMFaQ&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=cC2qctlVXd0qHMPvCyYvuVMqR8GU3DjTTqKJ0zjIFj8&s=rXIwWqf4U4HZS_bjUT3KfA9ARaV5YTb_kEcXWHnkt-c&e=>
>      >
>      >
>      > On Thu, Apr 30, 2020 at 9:56 PM suharto_anggono--- via R-devel <
>      > r-devel using r-project.org <mailto: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).
>      >>
>      >> ______________________________________________
>      >> R-devel using r-project.org <mailto:R-devel using r-project.org> mailing list
>      >>
>     https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Ddevel&d=DwICAg&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=776IovW06eUHr1EDrabHLY7F47rU9CCUEItSDI96zc0&s=xN84DhkZeoxzn6SG0QTMpOGg2w_ThmjZmZymGUuD0Uw&e=
>      >>
>      >
>      >       [[alternative HTML version deleted]]
>      >
>      > ______________________________________________
>      > R-devel using r-project.org <mailto:R-devel using r-project.org> mailing list
>      >
>     https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Ddevel&d=DwICAg&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=776IovW06eUHr1EDrabHLY7F47rU9CCUEItSDI96zc0&s=xN84DhkZeoxzn6SG0QTMpOGg2w_ThmjZmZymGUuD0Uw&e=
>      >
> 
>     -- 
>     Hervé Pagès
> 
>     Program in Computational Biology
>     Division of Public Health Sciences
>     Fred Hutchinson Cancer Research Center
>     1100 Fairview Ave. N, M1-B514
>     P.O. Box 19024
>     Seattle, WA 98109-1024
> 
>     E-mail: hpages using fredhutch.org <mailto:hpages using fredhutch.org>
>     Phone:  (206) 667-5791
>     Fax:    (206) 667-1319
> 
>     ______________________________________________
>     R-devel using r-project.org <mailto:R-devel using r-project.org> mailing list
>     https://stat.ethz.ch/mailman/listinfo/r-devel
>     <https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Ddevel&d=DwMFaQ&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=cC2qctlVXd0qHMPvCyYvuVMqR8GU3DjTTqKJ0zjIFj8&s=COnDeGgHNnHJlLLZOznMlhcaFU1nIRlkaSbssvlrMvw&e=>
> 

-- 
Hervé Pagès

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpages using fredhutch.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319