Re: [Rd] Questions about calls and formulas

From: Erich Neuwirth <erich.neuwirth_at_univie.ac.at>
Date: Mon 22 Aug 2005 - 22:45:02 GMT

>

>>(foo <- eval(substitute(x ~ g * h, list(x = as.name("weights")))))

>
> weights ~ g * h
>
>>class(foo)

>
> [1] "formula"
>
>

  ff<-formula("x~g*h")
  (foo<-eval(substitute(ff,list(x=as.name("weights")))))

gives

  x ~ g * h

what needs to be done to ff for the substitution to work?

I found a way of doing it using string substitution and applying formula (instead of as.call) to the string, but I would like to be able to do it using substitution.

This is what I currently do:

  myexpr<-paste("weights ~",strsplit(deparse(m$formula),"~")[[1]][2])   m$formula<-formula(myexpr)

-- 
Erich Neuwirth, Didactic Center for Computer Science
University of Vienna
Visit our SunSITE at http://sunsite.univie.ac.at
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Received on Tue Aug 23 08:49:46 2005

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