Hi. Thanks once more for the swift response. This solution works pretty well. The only small glitch is if I pass the function an argument with the same name as the function argument. That is, suppose "x" is the argument name in my user-defined function, and that object "x" does not exist. If I call the function f(x), i.e., using the non-existent object x as the argument value, then the function says that x exists.
Here is my example log: >chkex5 <- function(objn){ + c(exob=exists(deparse(substitute(objn)))) + } >exists("objn") [1] FALSE >chkex5(objn) exob TRUE > But I suppose I can live with this. Thanks again! -- TMK -- 212-460-5430 home 917-656-5351 cell >From: "Liaw, Andy" <[EMAIL PROTECTED]> >To: "Talbot Katz" <[EMAIL PROTECTED]>,r-help@stat.math.ethz.ch >Subject: RE: [R] Testing for existence inside a function >Date: Tue, 15 May 2007 11:41:17 -0400 > >Just need a bit more work: > >R> f <- function(x) exists(deparse(substitute(x))) >R> f(y) >[1] FALSE >R> y <- 1 >R> f(y) >[1] TRUE >R> f(z) >[1] FALSE > >Andy > >From: Talbot Katz > > > > Hi, Andy. > > > > Thank you for the quick response! Unfortunately, none of > > these are exactly > > what I'm looking for. I'm looking for the following: > > Suppose object y > > exists and object z does not exist. If I pass y as the value of the > > argument to my function, I want to be able to verify, inside > > my function, > > the existence of y; similarly, if I pass z as the value of > > the argument, I > > want to be able to see, inside the function, that z doesn't exist. > > > > The missing function just checks whether the argument is > > missing; in my > > case, the argument is not missing, but the object may not > > exist. And the > > way you use the exists function inside the user-defined > > function doesn't > > test the argument to the user-defined function, it's just > > hard-coded for the > > object y. So I'm sorry if I wasn't clear before, and I hope > > this is clear > > now. Perhaps what I'm attempting to do is unavailable > > because it's a bad > > programming paradigm. But even an explanation if that's the > > case would be > > appreciated. > > > > -- TMK -- > > 212-460-5430 home > > 917-656-5351 cell > > > > > > > > >From: "Liaw, Andy" <[EMAIL PROTECTED]> > > >To: "Talbot Katz" <[EMAIL PROTECTED]>,r-help@stat.math.ethz.ch > > >Subject: RE: [R] Testing for existence inside a function [Broadcast] > > >Date: Tue, 15 May 2007 11:03:12 -0400 > > > > > >Not sure which one you want, but the following should cover it: > > > > > >R> f <- function(x) c(x=missing(x), y=exists("y")) > > >R> f(1) > > > x y > > >FALSE FALSE > > >R> f() > > > x y > > > TRUE FALSE > > >R> y <- 1 > > >R> f() > > > x y > > >TRUE TRUE > > >R> f(1) > > > x y > > >FALSE TRUE > > > > > >Andy > > > > > >From: Talbot Katz > > > > > > > > Hi. > > > > > > > > I'm having trouble testing for existence of an object inside > > > > a function. > > > > > > > > Suppose I have a function: > > > > > > > > f<-function(x){ > > > > ... > > > > } > > > > > > > > and I call it with argument y: > > > > > > > > f(y) > > > > > > > > I'd like to check inside the function whether argument y > > > > exists. Is this > > > > possible, or do I have to either check outside the function > > > > or pass the name > > > > of the argument as a separate argument? > > > > > > > > If I do exists(x) or exists(eval(x)) inside the function and > > > > y does not > > > > exist, it generates an error message. If I do exists("x") it > > > > says that x > > > > exists even if y does not. If I had a separate argument to > > > > hold the text > > > > string "y" then I could check that. But is it possible > > to check the > > > > existence of the argument inside the function without passing > > > > its name as a > > > > separate argument? > > > > > > > > Thanks! > > > > > > > > -- TMK -- > > > > 212-460-5430 home > > > > 917-656-5351 cell > > > > > > > > ______________________________________________ > > > > R-help@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. > > > > > > > > > > > > > > > > > > > > >------------------------------------------------------------- > > ----------------- > > >Notice: This e-mail message, together with any attachments, contains > > >information of Merck & Co., Inc. (One Merck Drive, > > Whitehouse Station, > > >New Jersey, USA 08889), and/or its affiliates (which may be known > > >outside the United States as Merck Frosst, Merck Sharp & Dohme or MSD > > >and in Japan, as Banyu - direct contact information for affiliates is > > >available at http://www.merck.com/contact/contacts.html) that may be > > >confidential, proprietary copyrighted and/or legally > > privileged. It is > > >intended solely for the use of the individual or entity named on this > > >message. If you are not the intended recipient, and have > > received this > > >message in error, please notify us immediately by reply > > e-mail and then > > >delete it from your system. > > > > > >------------------------------------------------------------- > > ----------------- > > > > > > > > > > >------------------------------------------------------------------------------ >Notice: This e-mail message, together with any attachments...{{dropped}} ______________________________________________ R-help@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.