[R] R design (was "Variable passed to function not used in function in select)

[Rolf Turner]

On 12/11/2008, at 11:29 AM, Peter Dalgaard wrote:

> Ben Bolker wrote:
>
>>
>>   Sometime soon when I have the time and energy I will start
>> campaigning for an additional "drop" argument to subset that
>> does what one expects (!!??) with subsetted factor variables ...
>
> Not that one again! For at least one other value of one, the  
> expectation
> is the opposite: Factor levels do not go away just because they happen
> not to be present in data.
>
> fct <- lapply(dd, is.factor)
> dd[fct] <- lapply(dd[fct], "[", drop=TRUE)
>
> and begone with it...

(Don't you mean ``be done with it''?)

What would break if subset.default() were changed to:

function (x, subset, drop=FALSE, ...)
{
     if (!is.logical(subset))
         stop("'subset' must be logical")
     x[subset & !is.na(subset),drop=drop]
}

???

	cheers,

		Rolf

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