[Rd] hist() with option "sub" (PR#2492)

[ligges@statistik.uni-dortmund.de]

jerome@hivnet.ubc.ca wrote:
> 
> Full_Name: Jerome Asselin
> Version: 1.6.2
> OS: redhat linux 7.2
> Submission from: (NULL) (142.103.173.179)
> 
> This is certainly not a big problem, but should there really
> be a warning message when I run this?
> 
> > x <- c(1,1,2,2,2,2,3,3)
> > hist(x,sub="Sub Title")
> Warning messages:
> 1: parameter "sub" couldn't be set in high-level plot() function
> 2: parameter "sub" couldn't be set in high-level plot() function
> 
> The sub title DOES show on the graph. I believe the warning
> message is generated by axis() which does not deal with the
> parameter "sub".
> 
> The hist() help file says:
>      ...: further graphical parameters to `title' and `axis'.
> 
> I am aware of the challenges of dealing with dots (...) in
> functions. Perhaps just a note in the help file about this
> would be the best way to keep the code simple.
> 
> Regards,
> Jerome
> 

This is very common. You will see similar warnings (Note: warnings, not
errors!)  for many high-level plot functions with many graphical
arguments. It would be a bad idea to mention that on almost every
high-level plot funtion's help page, I think. Nevertheless, it might be
worth to mention it in the FAQs (Kurt ?), because we see questions
(rather than bug reports without apparent reason) on R-help quite
regularly (about once a month, I guess).

BTW: Martin Maechler addressed the underlying "problem" in his R-devel
message:

 Subject: [Rd] Changing "..." inside a function: impossible? desirable?
    Date: Tue, 17 Dec 2002 19:07:08

where "problem" means that it is impossible (at least not easily with a
reasonable amount of code) to write code using "..." that avoids the
warning messages.

Uwe Ligges