[R] defining a template for functions via do.call and substitute.

[john.gavin@ubs.com]

Hi,

Many thanks for the responses which solved my problem.

Fyi, my actual application is

copulaClayton <- function(u, v, alpha) 
  (u^-alpha + v^-alpha - 1)^(-1/alpha)
g <- function(){}
body(g) <- do.call("substitute", list(body(copulaClayton), 
  list(u = as.name("w"), v = quote(pnorm(var - qnorm(w))))))
formals(g) <- alist(w=, var=, alpha=)
g

and the substitutions seem to be working fine.

Thanks to 
Liaw, Andy [andy_liaw at merck.com]
Dimitris Rizopoulos [dimitris.rizopoulos at med.kuleuven.ac.be]
Bert Gunter [gunter.berton at gene.com] and
Thomas Lumley [tlumley at u.washington.edu],
Gabor Grothendieck <ggrothendieck at myway.com>

Regards,

John.

-----Original Message-----
From: Gavin, John 
Sent: 29 September 2004 12:17
To: 'r-help at stat.math.ethz.ch'
Subject: defining a template for functions via do.call and substitute.

Hi,

Given a function

  fun <- function(a, b) a + b

how do I generate the function 'function(x, y) x + y'?

Working from the help files and Bill Venables' R-news article (June 2002),
I have tried various permutations with substitute without success. 
e.g.
  do.call("substitute", list(fun, list(a = as.name("x"), b = as.name("y"))))

Regards,

John.

John Gavin <john.gavin at ubs.com>,
Quantitative Risk Models and Statistics,
UBS Investment Bank, 6th floor, 
100 Liverpool St., London EC2M 2RH, UK.
Phone +44 (0) 207 567 4289
Fax   +44 (0) 207 568 5352

Visit our website at http://www.ubs.com

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