[R] R function writing question

[Rachel Merriman]

Hi there!
I'm looking for a better way of getting the following code working --
can you help?  Instead of having to type in:

binarymissing(y ~ x1 + x2,data=mydata,na.action=na.keep)

as my function call, I would prefer not having to type in
na.action=na.keep    each time as this will always be the same.

The function na.keep is simply:       na.keep <- function(X){X}

The first few lines of the function binarymissing are:

binarymissing<- function (formula, surrogates=NULL, data = sys.parent(),
weights,na.action)
{
    mf <- match.call()
    mf[[1]] <- as.name("model.frame")
    mf <- eval(mf, sys.frame(sys.parent()))
    Y <- model.extract(mf,response)
   Terms <- attr(mf,"terms")
    X <- model.matrix(Terms,mf)
...
}

I've tried a few different things that haven't worked:  for example if I
put    na.action=na.keep    on the first line of function as my default,
the match.call line doesn't pick up the na.action value for some
reason.  Then when I use   model.matrix   it strips out all my missing
values (i.e. na.action=na.omit not na.keep) which is not what I want!
 Hopefully I have made this problem clear enough to you...  I'd really
appreciate your help!

Cheers,
Rachel

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