> I am using the ... argument to parmeterize a user define fn to accept > multiple input objects. I subsquently save all these data as a list. > Question: what is the best way to recover or extract the original object > names that were fed to the fn?
The following function, ellipsisInfo, returns character strings representing the actual arguments to the function. If the function was called with tags on the arguments, as in ellipsisInfo(tag=argument), it makes those tags the names on the returned character vector. It does not evaluate the ... arguments, so you don't run into problems with evaluating arguments too soon or evaluating ones that should not be evaluated most of the time. ellipsisInfo <- function(...) { # get the unevaluated expressions given as arguments unevaluatedArgs <- substitute(...()) # convert those expressions to text (truncate to single line) unevaluatedArgsAsText <- vapply(unevaluatedArgs, function(a)deparse(a)[1], "") unevaluatedArgsAsText } E.g., > i <- ellipsisInfo(x, log(10), e=exp(1), onProblem=stop("there was a problem")) > i "x" "log(10)" e "exp(1)" onProblem "stop(\"there was a problem\")" > ifelse(names(i)=="", i, names(i)) # use tag if supplied, otherwise argument > itself [1] "x" "log(10)" "e" [4] "onProblem" Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On > Behalf > Of Dan Abner > Sent: Friday, October 18, 2013 9:06 AM > To: r-help@r-project.org > Subject: [R] Recovering object names when using the ... argument in a fn XXXX > > Hi all, > > I am using the ... argument to parmeterize a user define fn to accept > multiple input objects. I subsquently save all these data as a list. > Question: what is the best way to recover or extract the original object > names that were fed to the fn? > > Thanks, > > Dan > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org 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@r-project.org 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.