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...{{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.