R devel - Sep 2009 - what should names(x) be padded with when length(x) is increased?

R version 2.10.0 Under development (unstable) (2009-09-08 r49628)

Here are two somewhat related questions.

First, when we attach a too short names vector to a vector
the names vector is padded with NA's to the length of the
main vector:  E.g.,
   > x<-1:3
   > names(x)<-c("One","Two")
   > str(x)
    Named int [1:3] 1 2 3
    - attr(*, "names")= chr [1:3] "One" "Two" NA
I expected this length mismatch to cause an error, but I am
biassed by my long usage of S and S+.  Is the extension by
padding with NA what is wanted?

Second, if we extend a named vector with length<- the main
vector is padded with NA's but the names are padded with
empty strings.  Should those be NA's?

   > x<-1:3
   > names(x)<-c("One","Two")
   > length(x)<-4
   > str(x)
    Named int [1:4] 1 2 3 NA
    - attr(*, "names")= chr [1:4] "One" "Two" NA
""

The names "" and NA act alike in that subscript by either
returns structure(NA, names=NA_character_), but they
print differently
   > x
    One  Two <NA>
     1    2    3   NA


Bill Dunlap
TIBCO Software Inc - Spotfire Division
wdunlap tibco.com

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On Fri, Sep 18, 2009 at 6:34 PM, William Dunlap <wdunlap at tibco.com>
wrote:
> R version 2.10.0 Under development (unstable) (2009-09-08 r49628)
>
> Here are two somewhat related questions.
>
> First, when we attach a too short names vector to a vector
> the names vector is padded with NA's to the length of the
> main vector: ?E.g.,
> ? > x<-1:3
> ? > names(x)<-c("One","Two")
> ? > str(x)
> ? ?Named int [1:3] 1 2 3
> ? ?- attr(*, "names")= chr [1:3] "One" "Two"
NA
> I expected this length mismatch to cause an error, but I am
> biassed by my long usage of S and S+. ?Is the extension by
> padding with NA what is wanted?
>
> Second, if we extend a named vector with length<- the main
> vector is padded with NA's but the names are padded with
> empty strings. ?Should those be NA's?
>
> ? > x<-1:3
> ? > names(x)<-c("One","Two")
> ? > length(x)<-4
> ? > str(x)
> ? ?Named int [1:4] 1 2 3 NA
> ? ?- attr(*, "names")= chr [1:4] "One" "Two"
NA ""
>
> The names "" and NA act alike in that subscript by either
> returns structure(NA, names=NA_character_), but they
> print differently
> ? > x
> ? ?One ?Two <NA>
> ? ? 1 ? ?2 ? ?3 ? NA
>
>
> Bill Dunlap
> TIBCO Software Inc - Spotfire Division
> wdunlap tibco.com
>
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