[Rd] what should names(x) be padded with when length(x) is increased?

[Gabor Grothendieck]

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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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