From: Talbot Katz <topkatz_at_msn.com>

Date: Tue, 15 May 2007 11:30:31 -0400

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. Received on Tue 15 May 2007 - 15:36:21 GMT

Date: Tue, 15 May 2007 11:30:31 -0400

*>From: "Liaw, Andy" <andy_liaw_at_merck.com>
**>To: "Talbot Katz" <topkatz_at_msn.com>,r-help_at_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_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.
**> >
**> >
**> >
**>
**>
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