R help - Oct 2010 - Question on passing the subset argument to an lm wrapper

Hello,

How would you go about handling the following situation?
This is on R 2.12.0 on Ubuntu 32-bit.

I have a wrapper function to lm.  I want to pass in a
subset argument.  First, I just thought I'd use "...".

## make example reproducible
set.seed(123)
df1 <- data.frame(age = rnorm(100, 50, 10),
                   bmi = rnorm(100, 30, sd = 2))

## create a wrapper using "..."
testlm <- function(formula, ...) {
   lm(formula, data = df1, ...)
}

 > testlm(bmi ~ age, subset = age > 50)

Error in eval(expr, envir, enclos) :
   ..1 used in an incorrect context, no ... to look in

I found some other examples of this error message,
but couldn't piece together how it fits in with this
example.

Next, I tried specifying a subset argument.

testlm2 <- function(formula, subset) {
   lm(formula, data = df1, subset = subset)
}

 > testlm2(bmi ~ age, subset = age > 50)

Error in xj[i] : invalid subscript type 'closure'

I also don't understand this one.

Any pointers on if I'm just missing the easy
solution to do what I want?  Any explanations
as to the above behavior (I know it has to do
with model.frame, but not sure how) would also
be greatly appreciated!

Thanks!
--Erik

On Sun, 24 Oct 2010, Erik Iverson wrote:
> Hello,
>
> How would you go about handling the following situation?
> This is on R 2.12.0 on Ubuntu 32-bit.
>
> I have a wrapper function to lm.  I want to pass in a
> subset argument.  First, I just thought I'd use "...".
The subset arg needs to be unevaluated until lm() - or whatever function 
- is called in your function.

The canonical advice for this kind of question about passing unevaluated 
args is to study the first lines of the function lm noting what it does 
with objects cl <- match.call() and mf <- match.call( expand.dots = FALSE 
).

Something like this might be what you want:

testlm2 <- function(formula, ...) {
     mc <- match.call()
     mc[[1]] <- as.name('lm')
     eval(mc)
}

testlm2(bmi ~ age, data= df1, subset = age > 50)

HTH,

Chuck

>
> ## make example reproducible
> set.seed(123)
> df1 <- data.frame(age = rnorm(100, 50, 10),
>                   bmi = rnorm(100, 30, sd = 2))
>
> ## create a wrapper using "..."
> testlm <- function(formula, ...) {
>  lm(formula, data = df1, ...)
> }
>
>>  testlm(bmi ~ age, subset = age > 50)
>
> Error in eval(expr, envir, enclos) :
>   ..1 used in an incorrect context, no ... to look in
>
> I found some other examples of this error message,
> but couldn't piece together how it fits in with this
> example.
>
> Next, I tried specifying a subset argument.
>
> testlm2 <- function(formula, subset) {
>  lm(formula, data = df1, subset = subset)
> }
>
>>  testlm2(bmi ~ age, subset = age > 50)
>
> Error in xj[i] : invalid subscript type 'closure'
>
> I also don't understand this one.
>
> Any pointers on if I'm just missing the easy
> solution to do what I want?  Any explanations
> as to the above behavior (I know it has to do
> with model.frame, but not sure how) would also
> be greatly appreciated!
>
> Thanks!
> --Erik
>
> ______________________________________________
> 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.
>
Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901

As workaround you can try this:

testlm <- function(formula, ...) {
 args <- list(formula, data = df1, ...)
 do.call(lm, args)
}

testlm(bmi ~ age, subset = df1$age > 50)



On Mon, Oct 25, 2010 at 2:16 AM, Erik Iverson <eriki@ccbr.umn.edu> wrote:
> Hello,
>
> How would you go about handling the following situation?
> This is on R 2.12.0 on Ubuntu 32-bit.
>
> I have a wrapper function to lm.  I want to pass in a
> subset argument.  First, I just thought I'd use "...".
>
> ## make example reproducible
> set.seed(123)
> df1 <- data.frame(age = rnorm(100, 50, 10),
>                  bmi = rnorm(100, 30, sd = 2))
>
> ## create a wrapper using "..."
> testlm <- function(formula, ...) {
>  lm(formula, data = df1, ...)
> }
>
> > testlm(bmi ~ age, subset = age > 50)
>
> Error in eval(expr, envir, enclos) :
>  ..1 used in an incorrect context, no ... to look in
>
> I found some other examples of this error message,
> but couldn't piece together how it fits in with this
> example.
>
> Next, I tried specifying a subset argument.
>
> testlm2 <- function(formula, subset) {
>  lm(formula, data = df1, subset = subset)
> }
>
> > testlm2(bmi ~ age, subset = age > 50)
>
> Error in xj[i] : invalid subscript type 'closure'
>
> I also don't understand this one.
>
> Any pointers on if I'm just missing the easy
> solution to do what I want?  Any explanations
> as to the above behavior (I know it has to do
> with model.frame, but not sure how) would also
> be greatly appreciated!
>
> Thanks!
> --Erik
>
> ______________________________________________
> R-help@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.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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