[R] Extracting the name of an object into a character string and vice versa

[David Winsemius]

On Dec 12, 2008, at 8:41 AM, Gabor Grothendieck wrote:

> Its a FAQ:
>
> http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-can-I-turn-a-string-into-a-variable_003f
>
> On Fri, Dec 12, 2008 at 8:30 AM, Philip Whittall
> <Philip.whittall at detica.com> wrote:
>>
>> I am still struggling to map a character string to an object name and
>> vice versa in R.
>> I thought the as.name() function might work, but observe the  
>> following
>> behaviour ...
>>
>>> attach(warpbreaks)
>>> levels(tension)
>> [1] "L" "M" "H"
>>> levels(as.name("tension"))
>> NULL
>>> objectname<-as.name("tension")
>>> objectname
>> tension
>>> levels(objectname)
>> NULL
>>
>> So even though it sets up a symbol, this symbol isn't recognised as  
>> an
>> object name by functions such as levels().
>>
>> I need 2 functions, call them A and B such that A("tension") yields  
>> the
>> object name tension which is recognised by functions and
>> B(tension) yields the character result "tension".

I see that your first request was satisfied. Your second one, that for  
a method to get as a character object the name of an object did not  
seem to get addressed. If tension is an R object (or a function call),  
try:
---a vector
 > tension <- vector()
 > as.character(bquote(tension))
[1] "tension"

--- a function with no arguments
 > as.character(bquote(ls()))
[1] "ls"

--- a function ( in this case the Extract or indexing function) with  
arguments

 > as.character(bquote(fit$terms))
[1] "$"     "fit"   "terms"

-- 
David Winsemius


>>
>>
>> Any suggestions would be greatly appreciated,
>>
>> Philip
>>
>>
>>
>>
>>
>>
>>
>>
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>
> ______________________________________________
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