You are confusing 'length' wih the number of characters in an element.
At least the present documentation is not incorrect!
> length("")
[1] 1
I think we normally say a string is non-empty (some say non-blank, but
others including me think " " is blank).
On Wed, 16 Aug 2006, Gregor Gorjanc wrote:
> Hello!
>
> It seems that prompt and continue argument of options() must be at least
> of length one i.e.
>
> > options(prompt="")
> Error in options(...) : prompt parameter invalid
> > options(prompt=" ")
> # bla, bla, ...
> > options(prompt="> ")
> > # bla, bla, ...
>
> > options(continue="")
> Error in options(...) : invalid continue parameter
> > options(continue=" ")
> > ls(
> )
>
> This could be properly documented as shown bellow. I do not think that
> it is worth bothering with modifying the code to allow empty prompt and
> continue argument.
>
> Cheers!
>
> Index: R/src/library/base/man/options.Rd
> ===================================================================
> --- options.Rd (revision 38890)
> +++ options.Rd (working copy)
> @@ -58,7 +58,7 @@
> like \code{x <- 1:3; x[5] <- 6}.}
>
> \item{\code{continue}:}{a string setting the prompt used for lines
> - which continue over one line.}
> + which continue over one line. Must be at least of length 1.}
>
> \item{\code{defaultPackages}:}{the packages that are attached by
> default when \R starts up. Initially set from value of the
> @@ -179,7 +179,7 @@
> argument.}
>
> \item{\code{prompt}:}{a string, used for \R's prompt; should usually
> - end in a blank (\code{" "}).}
> + end in a blank (\code{" "}). Must be at least of length 1.}
>
>
--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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