[R] colnames documentation

Uwe Ligges ligges at statistik.tu-dortmund.de
Sat Feb 11 20:08:14 CET 2012



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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