[R] names not inherited in functions

[Charles C. Berry]

David,

I think you are looking for

 	deparse(substitute(var))

See

 	?deparse

Notice in

 	?data.frame

this bit:

      ...: these arguments are of either the form 'value' or 'tag =
           value'.  Component names are created based on the tag (if
           present) or THE DEPARSED ARGUMENT ITSELF. [emphasis added]

Chuck


On Fri, 17 Aug 2007, david dav wrote:

> Dear R list,
> After a huge delay, I come back to this question. Using names of
> variables inside a function is a problem I run into quite often.
> Maybe this little example should help to get my point:
> Suppose I want to make a function "llabel" to get the labels of the
> variables from a data frame.
> If no label is defined, "llabel" should return the name of the variable.
>
> 	library(Hmisc)
> 	v1 <- c(1,2)
> 	v2 <- c(1,2)
> 	v3 <- c(1,3)
> 	tablo <- data.frame(v1,v2,v3)
> 	rm(v1,v2,v3)
>
> 	label(tablo$v1) <- "var1"
> 	attach(tablo)
>
> # This does the trick on one variable.
> 	if (label(v1) !="") label(v1)  	else names(data.frame(v1))
> 	if (label(v2) !="") label(v2)  	else names(data.frame(v2))
>
> But if I call this statement in a "llabel" function,
>
> 	llabel <- function(var) {
> 			if (label(var) !="" )
> 				res <- label(var)
> 				else res <- names(data.frame(var))
> 		return (res) }
>
> I just get "var"s instead of the names when no label is defined :
>
> llabel(v1) # works
> llabel(v2) # gives "var" instead of "v2"
>
> Thanks for your help.
>
> David
>
>
> 2007/6/7, Uwe Ligges <ligges at statistik.uni-dortmund.de>:
>> Not sure what you are going to get. Can you shorten your functions and
>> specify some example data? Then please tell us what your expected result is.
>>
>> Best,
>> Uwe Ligges
>>
>>
>>
>>
>> david dav wrote:
>>> Dear all,
>>>
>>> I 'd like to keep the names of variables when calling them in a function.
>>> An example might help to understand my problem :
>>>
>>> The following function puts in a new data frame counts and percent of
>>> a data.frame called as "tablo"
>>> the step " nom.chiffr[1] <- names(vari) " is useless as names from the
>>> original data.frame aren't kept in the function environement.
>>>
>>> Hoping I use appropriate R-vocabulary, I thank you for your help
>>>
>>> David
>>>
>>> descriptif <- function (tablo) {
>>>       descriptifvar <- function (vari) {
>>>               table(vari)
>>>               length(vari[!is.na(vari)])
>>>               chiffr <- cbind(table(vari),100*table(vari)/(length(vari[!is.na(vari)])))
>>>               nom.chiffr <- rep(NA, dim(table(vari)))
>>>               if (is.null(names(vari))) nom.chiffr[1] <- paste(i,"") else
>>>               nom.chiffr[1] <- names(vari)
>>>               chiffr <- data.frame (  names(table(vari)),chiffr)
>>>               rownames(chiffr) <- NULL
>>>               chiffr <- data.frame (nom.chiffr, chiffr)
>>>       return(chiffr)
>>>       }
>>>
>>>       res <- rep(NA, 4)
>>>       for (i in 1 : ncol(tablo))
>>>               res <- rbind(res,descriptifvar(tablo[,i]))
>>>       colnames(res) <- c("variable", "niveau", "effectif", "pourcentage")
>>> return(res[-1,])
>>> }
>>> # NB I used this function on a data.frame with only factors in
>>>
>>> ______________________________________________
>>> R-help at stat.math.ethz.ch mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901