[Rd] as.character(list(NA))

[Robert McGehee]

Also perhaps a surprise that the behavior depends on the mode of the NA. 

> is.na(as.character(list(NA_real_)))
[1] FALSE
> is.na(as.character(list(NA_character_)))
[1] TRUE

Does this mean deparse() preserves NA-ness for NA_character_ but not NA_real_?


-----Original Message-----
From: R-devel [mailto:r-devel-bounces at r-project.org] On Behalf Of Hervé Pagès
Sent: Monday, January 22, 2018 2:01 PM
To: William Dunlap <wdunlap at tibco.com>; Patrick Perry <pperry at stern.nyu.edu>
Cc: r-devel at r-project.org
Subject: Re: [Rd] as.character(list(NA))

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
>>
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Hervé Pagès

Program in Computational Biology
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