> Date: 18 Mar 2004 23:52:47 +0100 > From: Peter Dalgaard <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Cc: <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]>, <[EMAIL > PROTECTED]> > Subject: Re: [R] substitute question > > > "Gabor Grothendieck" <[EMAIL PROTECTED]> writes: > > > From: Peter Dalgaard <[EMAIL PROTECTED]> > > > (The real pain in these examples is that substitute autoquotes its > > > expr argument. Therefore, when you want to modify an expression that > > > is already stored in a variable, you need an extra outer layer of > > > eval(substitute(...)) to poke the content of the variable into the > > > inner substitute. An "esub" function with standard evaluation > > > semantics would make this much easier.) > > > > That is one of the frustrations of using substitute. > > > > The other is that even if you do perform two levels of substitute, > > as I have been trying, you still can't count on it working for > > an arbitrary unevaluated expression, as my examples show. > > Er, I don't think so. All I have seen is a couple of cases where you > tried to pass something that was not a language object (e.g. a > function as opposed to an expression or call generating a function.) > >
The parse/deparse one definitely is an expression: > z <- parse(text=deparse(f)) > class(z);mode(z);typeof(z) [1] "expression" [1] "expression" [1] "expression" In the other one, it is not an expression in the inner substitute but should be by the time it gets to the outer one since I explicitly added expression(...). It is expanded which shows it did do that part right. ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
