R help - Jun 2006 - Using data=x or subset=y in user-defined functions

Dear list members,

In some of my functions, I attach the data internally to allow subset
commands or to specify a data frame. This works well except for cases
where there is a "masking" conflict (which returns a warning). I see
some alternative listed in ?attach, but I'm not sure which of them do
what I'd like. Any suggestions?

Below is how I've been setting up my functions:

eg.function <- function(x, data=NULL, subset=NULL, ...) {

# Set up environment
on.exit(detach(data))
attach(data)
if(!is.null(subset)) {
    data<-subset(data,subset)
detach(data)
attach(data)
}
subset = NULL
 
# Function body here
output <- x   
return(output)
}

Thanks!

Manuel

I suggest you investigate with().

On Wed, 7 Jun 2006, Manuel Morales wrote:
> Dear list members,
>
> In some of my functions, I attach the data internally to allow subset
> commands or to specify a data frame. This works well except for cases
> where there is a "masking" conflict (which returns a warning). I
see
> some alternative listed in ?attach, but I'm not sure which of them do
> what I'd like. Any suggestions?
>
> Below is how I've been setting up my functions:
>
> eg.function <- function(x, data=NULL, subset=NULL, ...) {
>
> # Set up environment
> on.exit(detach(data))
> attach(data)
> if(!is.null(subset)) {
>    data<-subset(data,subset)
> detach(data)
> attach(data)
> }
> subset = NULL
>
> # Function body here
> output <- x
> return(output)
> }
>
> Thanks!
>
> Manuel
>
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>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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