[R] Building the call of an arbitrary function

[Gabor Grothendieck]

Try this.   We use do.call to call f with the args defined by ...
except that we replace the first arg with ..1+a (where ..1 means
first arg in R):

F <- function(f, a)
          function(...) do.call(match.fun(f), replace(list(...), 1, ..1 + a))
g <- F("+", 1000)
g(1,2) # 1003


On 9/17/06, Vincent Goulet <vincent.goulet at act.ulaval.ca> wrote:
> Hy all,
>
> Is there a direct way to build the complete function call of an arbitrary
> function?
>
> Here's what I want to do. A function will build a function which will itself
> call a probability density function for some law given in argument to the
> first function:
>
> > f("gamma", 1000)
>
> will return, say,
>
> function(x, shape, rate, scale = 1/rate)
>    dgamma(x + 1000, shape, rate, scale = 1/rate)
>
> (Notice that the arguments of the output function are those of dgamma().)
>
> I tried all sorts of combinations of call(), formals(), args() et al. to no
> avail. But then, I avoided, so far, to build the whole thing as a character
> string. Would it be the only option?
>
> Thanks for any help.
>
> --
>  Vincent Goulet, Professeur agrégé
>  École d'actuariat
>  Université Laval, Québec
>  Vincent.Goulet at act.ulaval.ca   http://vgoulet.act.ulaval.ca
>
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