R help - Jan 2013 - Unexpected behavior with abbreviation of an argument to paste

R 2.15.1
OS X

Colleagues,

I encountered the following unexpected behavior today:

The following command yielded the expected result:
	paste(c("TEXT1", "TEXT2"), collapse="|")
Result:
	[1] "TEXT1|TEXT2"

However, abbreviating "collapse" by even one character:
	paste(c("TEXT1", "TEXT2"), collaps="|") 
 yielded the following:
	[1] "TEXT1 |" "TEXT2 |" >

My experience has been that one can abbreviate these options as long as there is
no ambiguity.  For example, the "ignore.case" argument for grep can be
abbreviated to "ig" (shortening it to a single character creates an
ambiguity).

Is there something special about "collapse" that I am missing?

Dennis

Dennis Fisher MD
P < (The "P Less Than" Company)
Phone: 1-866-PLessThan (1-866-753-7784)
Fax: 1-866-PLessThan (1-866-753-7784)
www.PLessThan.com

Hi Dennis: One of  function argument matching rules in R that  arguments
after the dotdotdot have to be matched exactly ( see code for paste below )
so that's why your attempt doesn't work. But I would have been surprised
also so I'm not trying to imply that one should know which functions have
arguments after dotdotdot and which don't.

#============================================================
paste
function (..., sep = " ", collapse = NULL)
.Internal(paste(list(...), sep, collapse))
<bytecode: 0x01ea9ec4>
<environment: namespace:base>


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On Jan 27, 2013, at 4:10 PM, Dennis Fisher wrote:
> R 2.15.1
> OS X
>
> Colleagues,
>
> I encountered the following unexpected behavior today:
>
> The following command yielded the expected result:
> 	paste(c("TEXT1", "TEXT2"), collapse="|")
> Result:
> 	[1] "TEXT1|TEXT2"
>
> However, abbreviating "collapse" by even one character:
> 	paste(c("TEXT1", "TEXT2"), collaps="|")
> yielded the following:
> 	[1] "TEXT1 |" "TEXT2 |" >
>
> My experience has been that one can abbreviate these options as long  
> as there is no ambiguity.  For example, the "ignore.case"
argument
> for grep can be abbreviated to "ig" (shortening it to a single  
> character creates an ambiguity).
>
> Is there something special about "collapse" that I am missing?
What you are missing is not special about 'collapse', but is rather a  
feature shared by any argument after the "dots" in a function's  
argument list.

-- 

David Winsemius, MD
Alameda, CA, USA