[Rd] paste(character(0), collapse="", recycle0=FALSE) should be ""
Gabriel Becker
g@bembecker @end|ng |rom gm@||@com
Fri May 22 20:26:43 CEST 2020
I understand that this is consistent but it also strikes me as an enormous
'gotcha' of a magnitude that 'we' are trying to avoid/smooth over at this
point in user-facing R space.
For the record I'm not suggesting it should return something other than "",
and in particular I'm not arguing that any call to paste *that does not
return an error* with non-NULL collapse should return a character vector of
length one.
Rather I'm pointing out that it could (perhaps should, imo) simply be an
error, which is also consistent, in the strict sense, with
previous behavior in that it is the developer simply declining to extend
the recycle0 argument to the full parameter space (there is no rule that
says we must do so, arguments whose use is incompatible with other
arguments can be reasonable and called for).
I don't feel feel super strongly that reeturning "" in this and similar
cases horrible and should never happen, but i'd bet dollars to donuts that
to the extent that behavior occurs it will be a disproportionately major
source of bugs, and i think thats at least worth considering in addition to
pure consistency.
~G
On Fri, May 22, 2020 at 9:50 AM William Dunlap <wdunlap using tibco.com> wrote:
> I agree with Herve, processing collapse happens last so collapse=non-NULL
> always leads to a single character string being returned, the same as
> paste(collapse=""). See the altPaste function I posted yesterday.
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
>
> On Fri, May 22, 2020 at 9:12 AM Hervé Pagès <hpages using fredhutch.org> wrote:
>
>> I think that
>>
>> paste(c("a", "b"), NULL, c("c", "d"), sep = " ", collapse = ",",
>> recycle0=TRUE)
>>
>> should just return an empty string and don't see why it needs to emit a
>> warning or raise an error. To me it does exactly what the user is asking
>> for, which is to change how the 3 arguments are recycled **before** the
>> 'sep' operation.
>>
>> The 'recycle0' argument has no business in the 'collapse' operation
>> (which comes after the 'sep' operation): this operation still behaves
>> like it always had.
>>
>> That's all there is to it.
>>
>> H.
>>
>>
>> On 5/22/20 03:00, Gabriel Becker wrote:
>> > Hi Martin et al,
>> >
>> >
>> >
>> > On Thu, May 21, 2020 at 9:42 AM Martin Maechler
>> > <maechler using stat.math.ethz.ch <mailto:maechler using stat.math.ethz.ch>> wrote:
>> >
>> > >>>>> 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).
>> >
>> >
>> > Herve makes a good point about when sep and collapse are both set. That
>> > said, if the user explicitly sets recycle0, Personally, I don't think
>> it
>> > should be silently ignored under any configuration of other arguments.
>> >
>> > If all of the arguments are to go into effect, the question then
>> becomes
>> > one of ordering, I think.
>> >
>> > Consider
>> >
>> > paste(c("a", "b"), NULL, c("c", "d"), sep = " ", collapse = ",",
>> > recycle0=TRUE)
>> >
>> > Currently that returns character(0), becuase the logic is
>> > essenttially (in pseudo-code)
>> >
>> > collapse(paste(c("a", "b"), NULL, c("c", "d"), sep = " ",
>> > recycle0=TRUE), collapse = ", ", recycle0=TRUE)
>> >
>> > -> collapse(character(0), collapse = ", " recycle0=TRUE)
>> >
>> > -> character(0)
>> >
>> > Now Bill Dunlap argued, fairly convincingly I think, that paste(...,
>> > collapse=<string>) should /always/ return a character vector of length
>> > exactly one. With recycle0, though, it will return "" via the
>> progression
>> >
>> > paste(c("a", "b"), NULL, c("c", "d"), sep = " ", collapse = ",",
>> > recycle0=TRUE)
>> >
>> > -> collapse(character(0), collapse = ", ")
>> >
>> > -> ""
>> >
>> >
>> > because recycle0 is still applied to the sep-based operation which
>> > occurs before collapse, thus leaving a vector of length 0 to collapse.
>> >
>> > That is consistent but seems unlikely to be what the user wanted, imho.
>> > I think if it does this there should be at least a warning when paste
>> > collapses to "" this way, if it is allowed at all (ie if mixing
>> > collapse=<string>and recycle0=TRUEis not simply made an error).
>> >
>> > I would like to hear others' thoughts as well though. @Pages, Herve
>> > <mailto:hpages using fredhutch.org> @William Dunlap
>> > <mailto:wdunlap using tibco.com> is "" what you envision as thee desired and
>> > useful behavior there?
>> >
>> > Best,
>> > ~G
>> >
>> >
>> >
>> > 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>
>> > >> <mailto: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=q5ueyHReS5hHK6TZ0dJ1N7Ro8dx-rsLHys8GrCugOls&s=o9ozvxBK-kVvAUFro7U1RrI5w0U8EPb0uyjQwMvOpt8&e=
>> >
>> > >>
>> > <
>> 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>
>> > <mailto: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>
>> > <mailto:R-devel using r-project.org <mailto:R-devel using r-project.org>>
>> > mailing list
>> > >> >>
>> > >>
>> >
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>> > >> >>
>> > >> >
>> > >> > [[alternative HTML version deleted]]
>> > >> >
>> > >> > ______________________________________________
>> > >> > R-devel using r-project.org <mailto:R-devel using r-project.org>
>> > <mailto:R-devel using r-project.org <mailto:R-devel using r-project.org>>
>> > mailing list
>> > >> >
>> > >>
>> >
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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 <mailto:hpages using fredhutch.org>
>> > <mailto: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>
>> > <mailto: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=q5ueyHReS5hHK6TZ0dJ1N7Ro8dx-rsLHys8GrCugOls&s=OLA7CqaU5uKeid1aGw41XJ_2Uq7JXbcwpPOrTWWG2v4&e=
>> >
>> > >>
>> > <
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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 <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=q5ueyHReS5hHK6TZ0dJ1N7Ro8dx-rsLHys8GrCugOls&s=OLA7CqaU5uKeid1aGw41XJ_2Uq7JXbcwpPOrTWWG2v4&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
>>
>
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