R devel - Jan 2018 - as.character(list(NA))

As of R Under development (unstable) (2018-01-19 r74138):

 > as.character(list(NA))
[1] "NA"

 > is.na(as.character(list(NA)))
[1] FALSE

On 20 January 2018 at 10:43, Patrick Perry wrote:
| As of R Under development (unstable) (2018-01-19 r74138):
| 
|  > as.character(list(NA))
| [1] "NA"
| 
|  > is.na(as.character(list(NA)))
| [1] FALSE

Are you aware that this is the same in R-release, and might be "on
purpose" ?

R> R.Version()$version.string
[1] "R version 3.4.3 (2017-11-30)"
R> as.character(list(NA))
[1] "NA"
R> is.na(as.character(list(NA)))
[1] FALSE
R> 

It is after all you who forces the as.character() and I don't think anybody
claims that to be a lossless operation from logical.  To wit:

R> is.na(list(NA))
[1] TRUE
R> 

Dirk

-- 
http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org

I believe that for a list as.character() applies deparse()  to each element
of the list.  deparse() does not preserve NA-ness, as it is intended to
make text that the parser can read.
> str(as.character(list(Na=NA, LglVec=c(TRUE,NA),
Function=function(x){x+1})))
 chr [1:3] "NA" "c(TRUE, NA)" "function (x) \n{\n    x
+ 1\n}"


Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Sat, Jan 20, 2018 at 7:43 AM, Patrick Perry <pperry at stern.nyu.edu>
wrote:
> As of R Under development (unstable) (2018-01-19 r74138):
>
> > as.character(list(NA))
> [1] "NA"
>
> > is.na(as.character(list(NA)))
> [1] FALSE
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
	[[alternative HTML version deleted]]

On 01/20/2018 08:24 AM, William Dunlap via R-devel
wrote:
> I believe that for a list as.character() applies deparse()  to each element
> of the list.  deparse() does not preserve NA-ness, as it is intended to
> make text that the parser can read.
> 
>> str(as.character(list(Na=NA, LglVec=c(TRUE,NA),
> Function=function(x){x+1})))
>   chr [1:3] "NA" "c(TRUE, NA)" "function (x) \n{\n
x + 1\n}"
> 
This really comes as a surprise though since coercion to all the
other atomic types (except raw) preserve the NAs.

And also as.character(unlist(list(NA))) preserves them.

H.
> 
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
> 
> On Sat, Jan 20, 2018 at 7:43 AM, Patrick Perry <pperry at
stern.nyu.edu> wrote:
> 
>> As of R Under development (unstable) (2018-01-19 r74138):
>>
>>> as.character(list(NA))
>> [1] "NA"
>>
>>> is.na(as.character(list(NA)))
>> [1] FALSE
>>
>> ______________________________________________
>> 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=VbamM9XRQOlfBakrmlrmQZ7DLgXZ-hhhFeLD-fKpoCo&s=Luhqwpr2bTltIA9Cy7kA4gwcQh16bla0S6OVe3Z09Xo&e>>
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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=VbamM9XRQOlfBakrmlrmQZ7DLgXZ-hhhFeLD-fKpoCo&s=Luhqwpr2bTltIA9Cy7kA4gwcQh16bla0S6OVe3Z09Xo&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