[Rd] paste(character(0), collapse="", recycle0=FALSE) should be ""
Martin Maechler
m@ech|er @end|ng |rom @t@t@m@th@ethz@ch
Thu May 21 18:42:32 CEST 2020
>>>>> Hervé Pagès
>>>>> on Fri, 15 May 2020 13:44:28 -0700 writes:
> 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.
Interesting, ..., and sounding somewhat convincing.
> 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
Just to summarize what I think we should know and agree (or be
be "disproven") and where this comes from ...
1) recycle0 is a new R 4.0.0 option in paste() / paste0() which by default
(recycle0 = FALSE) should (and *does* AFAIK) not change anything,
hence paste() / paste0() behave completely back-compatible
if recycle0 is kept to FALSE.
2) recycle0 = TRUE is meant to give different behavior, notably
0-length arguments (among '...') should result in 0-length results.
The above does not specify what this means in detail, see 3)
3) The current R 4.0.0 implementation (for which I'm primarily responsible)
and help(paste) are in accordance.
Notably the help page (Arguments -> 'recycle0' ; Details 1st para ; Examples)
says and shows how the 4.0.0 implementation has been meant to work.
4) Several provenly smart members of the R community argue that
both the implementation and the documentation of 'recycle0 =
TRUE' should be changed to be more logical / coherent / sensical ..
Is the above all correct in your view?
Assuming yes, I read basically two proposals, both agreeing
that recycle0 = TRUE should only ever apply to the action of 'sep'
but not the action of 'collapse'.
1) Bill and Hervé (I think) propose that 'recycle0' should have
no effect whenever 'collapse = <string>'
2) Gabe proposes that 'collapse = <string>' and 'recycle0 = TRUE'
should be declared incompatible and error. If going in that
direction, I could also see them to give a warning (and
continue as if recycle = FALSE).
I have not yet my mind up but would tend to agree to "you guys",
but I think that other R Core members should chime in, too.
Martin
>> 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
>> >>
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>> >>
>> >
>> > [[alternative HTML version deleted]]
>> >
>> > ______________________________________________
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>> >
>> 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
>>
>> ______________________________________________
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>>
> --
> 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
> ______________________________________________
> R-devel using r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
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