[R] for loop over dataframe without indices

[Thomas Lumley]

On Fri, 19 Dec 2003, Gabor Grothendieck wrote:
>
> What I now realize is that the thing that is oddly
> missing in R is that you can't do an apply over
> the rows of a dataframe (at least not without having
> it coerced to an array and the elements coerced to
> possibly different types).  The documentation does
> point this out.  Its not a bug but its an omission
> that seems deserving of being addressed.
>

Since mapply() applies a function to each 'row' of a list of vectors, ou
can achieve this effect with
	do.call("mapply", list(FUN,data.frame))
and also as a degenerate case of by():
	by(data.frame, row.names(data.frame), FUN)

These should probably be documented under apply()


	-thomas