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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