[R] Problem with all.equal and POSIXt.

[Rolf Turner]

On 13/09/2010, at 3:07 PM, Peter Ehlers wrote:

	<SNIP>

> I'm not sure that I would call this a bug, but it would seem
> helpful to return an appropriate error message or to coerce to
> POSIXct. Note that
> 
>  all.equal(as.POSIXct(x), as.POSIXct(x))
> 
> yields TRUE, as does using as.Date(x).


Well, I ***would*** call it a bug.  The all.equal() function is confusing
the length of x as a POSIXlt object (i.e. the length of its list components)
with the length of the (well hidden) list structure of x (i.e. 9).  This is
the wrong thing to do, so it's a bug.

I notice that there is an all.equal.POSIXct() method.  Maybe there should also be
an as.equal.POSIXlt() method --- which would just coerce its argument to POSIXct,
and then do NextMethod().

But maybe there's a Good Reason why R Core did not implement an as.equal.POSIXlt()
method --- i.e. it's dangerous to apply all.equa1() to POSIXlt objects.
Can't think why this should be, but.

	cheers,

		Rolf
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