R help - Feb 2012 - colnames documentation

Consider the following in R 2.14.1 (seems to still be the case in Rdevel):

x <- matrix(1:9, 3)
colnames(x) # NULL as expected
colnames(x, do.NULL = TRUE) # NULL -- since we didn't change the default
colnames(x, do.NULL = FALSE) # "col1" "col2"
"col3"

This doesn't really seem to square with the documentation which reads:

do.NULL: logical.  Should this create names if they are ?NULL??

The details section expounds and says:

If ?do.NULL? is ?FALSE?, a character vector (of length ?NROW(x)?
     or ?NCOL(x)?) is returned in any case, prepending ?prefix? to
     simple numbers, if there are no dimnames or the corresponding
     component of the dimnames is ?NULL?.

But I have to admit that I don't really get it. (The interpretation of
the docs; I understand the functionality) Could someone enlighten me?
Given what the details section says (and the behavior of the function
is), I'd expect something more like:

do.NULL: logical.  Is NULL an acceptable return value? If FALSE,
column names derived from prefix are returned.

Michael

PS -- In my searching, I think the link to the svn on the developer
page (http://developer.r-project.org/) is wrong: clicking it takes one
to what appears to be the same page: am I incorrect in assuming it
should link to http://svn.r-project.org/R for the current svn?

On 10.02.2012 04:53, R. Michael Weylandt wrote:
> Consider the following in R 2.14.1 (seems to still be the case in Rdevel):
>
> x<- matrix(1:9, 3)
> colnames(x) # NULL as expected
> colnames(x, do.NULL = TRUE) # NULL -- since we didn't change the
default
> colnames(x, do.NULL = FALSE) # "col1" "col2"
"col3"
>
> This doesn't really seem to square with the documentation which reads:
>
> do.NULL: logical.  Should this create names if they are ?NULL??
>
> The details section expounds and says:
>
> If ?do.NULL? is ?FALSE?, a character vector (of length ?NROW(x)?
>       or ?NCOL(x)?) is returned in any case, prepending ?prefix? to
>       simple numbers, if there are no dimnames or the corresponding
>       component of the dimnames is ?NULL?.
>
> But I have to admit that I don't really get it. (The interpretation of
> the docs; I understand the functionality) Could someone enlighten me?
> Given what the details section says (and the behavior of the function
> is), I'd expect something more like:
>
> do.NULL: logical.  Is NULL an acceptable return value? If FALSE,
> column names derived from prefix are returned.

Changed to

\item{do.NULL}{logical. If \code{FALSE} and names are \code{NULL}, names 
are created.}
> Michael
>
> PS -- In my searching, I think the link to the svn on the developer
> page (http://developer.r-project.org/) is wrong: clicking it takes one
> to what appears to be the same page: am I incorrect in assuming it
> should link to http://svn.r-project.org/R for the current svn?

I think you followed the link to the svn sources of that developer page 
(rather than the software R).

Uwe

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