?if

I am trying to introduce a class of senior undergraduates to the 
values and advantages of R for their statistical needs.  
Unfortunately, little (and inconsequential) inconsistencies such as 
these do little to improve their confidence in the application.  It is 
not that I needed help on the topics, but my students may, and when 
the two tools they know how to use, ? and apropos(), fail, I get 
panicked e-mails...  I just thought the list would want to know.

-John


On 12-Feb-05, at 7:47 PM, Rob J Goedman wrote:

Thanks Byron.

You're right. In fact ?"if" works fine as well.

You do have the November version of R.app. The R.app on Simon's site 
will give you a faster
response if it can't find help on a topic.

Rob

On Feb 12, 2005, at 5:04 PM, Dr. John R. Vokey wrote:

help(if) (or other control control structures aside from if) gives 
the same non-result, unless quoted (as noted).  A related error 
occurs with apropos(if)---it returns a syntax error.

The version is: This version:
	Version 1.01

Requires:
	R  2.0.1 (2004-11-15)
	Framework Version


On 12-Feb-05, at 5:40 PM, Byron Ellis wrote:

Actually there is help for control structures, help("if") works 
just fine. The problem is ? is that R's parser treats ? as an 
operator with unary and binary forms when, in fact, its not really 
an operator. ?if(TRUE) TRUE (any valid IF construct) will also give 
the help for 'if'. This is true for all platforms and probably has 
something to do with the fact that while "if" is bound directly to 
a primitive ( "if"(runif(1) < 0.5,TRUE,FALSE) is equivalent to 
if(runif(1) < 0.5) TRUE else FALSE) , the if bareword gets special 
handling in the parser.

On Feb 12, 2005, at 4:33 PM, Rob J Goedman wrote:

John,

Just to make sure, which configuration are you using?

Assuming the GUI (otherwise you would see a "+" instead of the ">" 
prompt), which version of
the R.app are you using? The creation date listed in Finder will 
do.

I think you noticed 2 issues. Right now, there is no ? help for 
control structures. You have to go
to the language reference manual. Secondly, newer versions of 
R.app (just the GUI part, as
released by Simon on http://www.rosuda.org/R/nightly/ ) will tell 
you if there is no help for
the requested topic.

Hope this helps,
Rob


On Feb 12, 2005, at 1:22 PM, Dr. John R. Vokey wrote:

? followed by any of the condition statements (or help() 
containing the condition statement)  does nothing (i.e., the help 
window fails to open), but the line is parsed in that the prompt 
`>' is returned.  Is this a parsing error in the help function, 
or (more likely) have I missed some deep R construct?
--
John


--
John R. Vokey, PhD
Professor
B.E.R.G. - Behaviour and Evolution Research Group
Micro-Cognition Laboratory
Department of Psychology & Neuroscience
University of Lethbridge
Lethbridge, Alberta T1K 3M4
CANADA

---
Byron Ellis (ellis@stat.harvard.edu)
"Oook" -- The Librarian

--
John R. Vokey, PhD
Professor
B.E.R.G. - Behaviour and Evolution Research Group
Micro-Cognition Laboratory
Department of Psychology & Neuroscience
University of Lethbridge
Lethbridge, Alberta T1K 3M4
CANADA