R devel - Oct 2001 - Characters subsetted with NA (was: Several R vs S-Plus issues)

Hello, R-devel!

I posted to R-help, and (inappropriately) to R-bugs, this R/S-Plus
difference:
> LETTERS[c(NA,2)] in S is c("","B"), but in R is
c("NA","B")
Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at> wrote:
> I think we do not want to change this. ...
> R> is.na(LETTERS[c(NA,2)])
  [1]  TRUE FALSE
> so we really have NA but it is printed as "NA" (and this might be
> another case where <NA> would be better).
This is merely a statement about is.na(), namely that it flags the string
"NA".  There is no distinction in R between the "NA" that
arises from
subsetting with a missing value, and the "NA" that represents Nabisco.
Note:
  R> all.equal(LETTERS[c(NA,2)][1], substring("NABISCO",1,2))
  [1] TRUE

R thinks I am missing data when I trade Nabisco, in the Netherlands/Antilles,
or through trader Neil Armstrong.  In each case, "" would more likely
indicate
a missing value; there is no stock with that ticker, country with that symbol,
or trader with those initials.

I'd think it would be easy to make is.na() flag "" instead of
"NA".  However,
I'm stuck at the definition:
  R> is.na
  .Primitive("is.na")
so I don't know how to change it (I'm a lousy developer, you see).

I propose again that we provide options(na.char="NA"), so users can
make their
own choice.  Thanks for listening!
					-- David Brahm (brahm@alum.mit.edu)
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To:
r-devel-request@stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._

David Brahm  <a215020@agate.fmr.com> writes:
>   R> is.na
>   .Primitive("is.na")
> so I don't know how to change it (I'm a lousy developer, you see).
> 
> I propose again that we provide options(na.char="NA"), so users
can make their
> own choice.  Thanks for listening!
Other's have been on the warpath re. this issue lately (and it's been
an annoyance for years - NorAdrenalin, Nitric Acid, etc.). It's not
unlikely to find a solution for 1.4, but probably not the one you are
proposing. Basically, we should have a *real* NA for string variables,
distinct from the character string "NA" and propagating like any other
NA's.

Inserting a value to substitute for missing could be handled
differently, e.g. via

replace.na <- function(x,r){x[is.na(x)]<-r; x}

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To:
r-devel-request@stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._

Peter Dalgaard <p.dalgaard@biostat.ku.dk> wrote:
> Basically, we should have a *real* NA for string variables, distinct from
> the character string "NA" and propagating like any other
NA's.
I could go for that.  How would it appear when cat()ed or print()ed?

		      -- David Brahm (brahm@alum.mit.edu)
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To:
r-devel-request@stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._