There is no perfect way to do this because you can write functions that depend on the order of evaluation of their arguments or that must evaluate some code in the body of the function before evaluating an argument (e.g., stats:::print.formula) or that don't evaluate them in the usual sense. However, print(ls.str(environment())), as the first line of the function, can be useful:
> trace(nls, quote(print(ls.str(environment())))) Tracing function "nls" in package "stats" [1] "nls" > d <- data.frame(x=log(1:10),y=1:10) > fit <- nls(y~a*x^b, data=d, start=c(a=1,b=1)) Tracing nls(y ~ a * x^b, data = d, start = c(a = 1, b = 1)) on entry algorithm : chr [1:3] "default" "plinear" "port" control : List of 5 $ maxiter : num 50 $ tol : num 1e-05 $ minFactor: num 0.000977 $ printEval: logi FALSE $ warnOnly : logi FALSE data : 'data.frame': 10 obs. of 2 variables: $ x: num 0 0.693 1.099 1.386 1.609 ... $ y: int 1 2 3 4 5 6 7 8 9 10 formula : Class 'formula' language y ~ a * x^b lower : num -Inf model : logi FALSE na.action : <missing> start : Named num [1:2] 1 1 subset : <missing> trace : logi FALSE upper : num Inf weights : <missing> Bill Dunlap TIBCO Software wdunlap tibco.com On Sat, Oct 8, 2016 at 7:21 AM, Christian Hoffmann <christ...@echoffmann.ch> wrote: > I try to print (names and) values of parameters of a function within that > function, like: > > F <- function(x, y, z=4, ...) { > > print("x = ", x, " , y = ", y, "... = " , ...) > > in a fashion that avoids the explicit mention of "x = ", x, " , y = ", y, > "... = " , ... > > Combinations of eval, substitute, formals, etc. should be able to do the > job, but I didn't find help online. > > Anyone lend a helping hand? > TIA Christian > > -- > Christian W. Hoffmann > CH - 8915 Hausen am Albis, Schweiz > Rigiblickstrasse 15 b, Tel.+41-44-7640853 > mailto: christ...@echoffmann.ch > home: www.echoffmann.ch > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posti > ng-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.