From: Jerome Asselin <jerome.asselin.stat_at_gmail.com>

Date: Fri, 29 Apr 2011 00:25:14 -0400

}

R-help_at_r-project.org 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 Fri 29 Apr 2011 - 04:29:17 GMT

Date: Fri, 29 Apr 2011 00:25:14 -0400

On Thu, 2011-04-28 at 23:08 -0400, Chee Chen wrote:

> Dear All,

*> I would like to define a function: f(x,y,z) with three arguments x,y,z, such that: given values for x,y, f(x,y,z) is still a function of z and that I am still allowed to find the root in terms of z when x,y are given.
**> For example: f(x,y,z) = x+y + (x^2-z), given x=1,y=3, f(1,3,z)= 1+3+1-z is a function of z, and then I can use R to find the root z=5.
**>
**> Thank you.
**> -Chee
*

Interesting exercise.

I've got this function, which I think it's doing what you're asking.

f <- function(x,y,z)

{

fcall <- match.call() fargs <- NULL if(fcall$x == "x") fargs <- c(fargs, "x") if(fcall$y == "y") fargs <- c(fargs, "y") if(fcall$z == "z") fargs <- c(fargs, "z") ffunargs <- as.list(fargs) names(ffunargs) <- fargs argslist <- list(fcall) ffun <- append(argslist, substitute( x+y + (x^2-z) ), after=0)[[1]] as.function(append(ffunargs, ffun))

}

This yields.

> f(3, 2, z)

function (z = "z")

3 + 2 + (3^2 - z)

<environment: 0x132fdb8>

> f(3, 2, z)(3)

[1] 11

I haven't figured out how to get rid of the default argument value shown here as 'z = "z"'. That doesn't prevent it to work, but it's less pretty. If you find a better way, let me know.

**HTH,
**

Jerome

R-help_at_r-project.org 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 Fri 29 Apr 2011 - 04:29:17 GMT

Archive maintained by Robert King, hosted by
the discipline of
statistics at the
University of Newcastle,
Australia.

Archive generated by hypermail 2.2.0, at Fri 29 Apr 2011 - 13:50:33 GMT.

*
Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help.
Please read the posting
guide before posting to the list.
*