R devel - May 2020 - paste(character(0), collapse="", recycle0=FALSE) should be ""

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 Herv? Pag?s <hpages at fredhutch.org 
> <mailto:hpages at 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 at r-project.org <mailto: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).
>      >>
>      >> ______________________________________________
>      >> R-devel at r-project.org <mailto:R-devel at
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 at r-project.org <mailto:R-devel at 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>
>
> 
>     -- 
>     Herv? Pag?s
> 
>     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 at fredhutch.org <mailto:hpages at fredhutch.org>
>     Phone:? (206) 667-5791
>     Fax:? ? (206) 667-1319
> 
>     ______________________________________________
>     R-devel at r-project.org <mailto:R-devel at 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=>
> 
-- 
Herv? Pag?s

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 at fredhutch.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319

>>>>> Herv? Pag?s 
>>>>>     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 Herv? (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 Herv? Pag?s <hpages at
fredhutch.org
    >> <mailto:hpages at 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 at r-project.org <mailto: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).
    >> >>
    >> >> ______________________________________________
    >> >> R-devel at r-project.org <mailto:R-devel at
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 at r-project.org <mailto:R-devel at
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
>> >
    >> 
    >> -- 
    >> Herv? Pag?s
    >> 
    >> 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 at fredhutch.org <mailto:hpages at
fredhutch.org>
    >> Phone:? (206) 667-5791
    >> Fax:? ? (206) 667-1319
    >> 
    >> ______________________________________________
    >> R-devel at r-project.org <mailto:R-devel at 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=>
    >> 

    > -- 
    > Herv? Pag?s

    > 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 at fredhutch.org
    > Phone:  (206) 667-5791
    > Fax:    (206) 667-1319

    > ______________________________________________
    > R-devel at r-project.org mailing list
    > https://stat.ethz.ch/mailman/listinfo/r-devel

> 1) Bill and Herv? (I think) propose that 'recycle0' should have
>   no effect whenever  'collapse = <string>'
I think that collapse=<string> should make paste() return a single string,
regardless of the value of recycle0.  E.g., I would like to see
> paste0("X",seq_len(3),collapse=", ", recycle0=TRUE)
[1] "X1, X2, X3"
> paste0("X",seq_len(0),collapse=", ", recycle0=TRUE)
[1] ""

Currently the latter gives character(0).

paste's collapse argument has traditionally acted after all the other
arguments were dealt with, as in the following not extensively tested
function.

altPaste <- function (..., collapse = NULL) {
    tmp <- paste(...)
    if (!is.null(collapse)) {
        paste(tmp, collapse=collapse)
    } else {
        tmp
    }
}

E.g., in post-R-4.0.0 R-devel
> altPaste("X", seq_len(3), sep="", collapse=",
")
[1] "X1, X2, X3"
> altPaste("X", seq_len(0), sep="", collapse=",
")
[1] "X"
> altPaste("X", seq_len(0), sep="", collapse=",
", recycle0=TRUE)
[1] ""

I think it would be good if the above function continued to act the same as
paste itself.

Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Thu, May 21, 2020 at 9:42 AM Martin Maechler <maechler at
stat.math.ethz.ch>
wrote:
> >>>>> Herv? Pag?s
> >>>>>     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 Herv? (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 Herv? Pag?s <hpages at
fredhutch.org
>     >> <mailto:hpages at 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 at r-project.org <mailto: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).
>     >> >>
>     >> >> ______________________________________________
>     >> >> R-devel at r-project.org <mailto:R-devel at
r-project.org> mailing
> list
>     >> >>
>     >>
>
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>> >>
>     >> >
>     >> >       [[alternative HTML version deleted]]
>     >> >
>     >> > ______________________________________________
>     >> > R-devel at r-project.org <mailto:R-devel at
r-project.org> mailing list
>     >> >
>     >>
>
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>> >
>     >>
>     >> --
>     >> Herv? Pag?s
>     >>
>     >> 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 at fredhutch.org <mailto:hpages at
fredhutch.org>
>     >> Phone:  (206) 667-5791
>     >> Fax:    (206) 667-1319
>     >>
>     >> ______________________________________________
>     >> R-devel at r-project.org <mailto:R-devel at
r-project.org> mailing list
>     >> https://stat.ethz.ch/mailman/listinfo/r-devel
>     >> <
>
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>
>     >>
>
>     > --
>     > Herv? Pag?s
>
>     > 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 at fredhutch.org
>     > Phone:  (206) 667-5791
>     > Fax:    (206) 667-1319
>
>     > ______________________________________________
>     > R-devel at r-project.org mailing list
>     > https://stat.ethz.ch/mailman/listinfo/r-devel
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
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Hi Martin et al,



On Thu, May 21, 2020 at 9:42 AM Martin Maechler <maechler at
stat.math.ethz.ch>
wrote:
> >>>>> Herv? Pag?s
> >>>>>     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 Herv? (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=TRUE is not simply made an error).

I would like to hear others' thoughts as well though. @Pages, Herve
<hpages at fredhutch.org> @William Dunlap <wdunlap at 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 Herv? Pag?s <hpages at
fredhutch.org
>     >> <mailto:hpages at 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 at r-project.org <mailto: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).
>     >> >>
>     >> >> ______________________________________________
>     >> >> R-devel at r-project.org <mailto:R-devel at
r-project.org> mailing
> list
>     >> >>
>     >>
>
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>> >>
>     >> >
>     >> >       [[alternative HTML version deleted]]
>     >> >
>     >> > ______________________________________________
>     >> > R-devel at r-project.org <mailto:R-devel at
r-project.org> mailing list
>     >> >
>     >>
>
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>> >
>     >>
>     >> --
>     >> Herv? Pag?s
>     >>
>     >> 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 at fredhutch.org <mailto:hpages at
fredhutch.org>
>     >> Phone:  (206) 667-5791
>     >> Fax:    (206) 667-1319
>     >>
>     >> ______________________________________________
>     >> R-devel at r-project.org <mailto:R-devel at
r-project.org> mailing list
>     >> https://stat.ethz.ch/mailman/listinfo/r-devel
>     >> <
>
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>
>     >>
>
>     > --
>     > Herv? Pag?s
>
>     > 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 at fredhutch.org
>     > Phone:  (206) 667-5791
>     > Fax:    (206) 667-1319
>
>     > ______________________________________________
>     > R-devel at r-project.org mailing list
>     > https://stat.ethz.ch/mailman/listinfo/r-devel
>
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