[Rd] bug in identical()? [Was: [R-sig-ME] Failure to load lme4 on Mac]

From: Simon Urbanek <simon.urbanek_at_r-project.org>
Date: Sat, 17 Jul 2010 15:49:08 -0400

Daniel,

thanks for the test case. I did run it in valgrind but nothing showed up, however ...

I'm starting to have a suspicion that this has something to do with identical() - look at this:

> identical(M1,M2)

[1] FALSE
> all(serialize(M1,NULL)==serialize(M2,NULL))
[1] TRUE
> identical(unserialize(serialize(M1,NULL)),unserialize(serialize(M2,NULL)))
[1] FALSE
> identical(unserialize(serialize(M1,NULL)),unserialize(serialize(M1,NULL)))
[1] FALSE So I think this may be a bug in identical() mainly because of the last one. I'll need to take identical() apart to see where it fails ... I'm CCing this to R-devel as the current issue seems more like an R issue so more eyes can have a look ...

Cheers,
Simon

[FWIW this is tested in today's R-devel (with valgrind level 2) on x86_64 OS X 10.6.4 with lme4 from CRAN and Matrix form R-devel Recommended]

On Jul 17, 2010, at 4:50 AM, Daniel Myall wrote:

> I've done some further testing (R 2.11.1) and the issue is not limited to Leopard.
>
> Using the test:
>
> library(lme4)
> y <- (1:20)*pi
> x <- (1:20)^2
> group <- gl(2,10)
> for (i in 1:10) {
> M1 <- lmer (y ~ x + ( x | group))
> M2 <- lmer (y ~ x + ( x | group))

> print(identical(M1,M2))

> }
>
> For CRAN lme4 and Matrix:
>
> 32 bit on Leopard: R CMD check fails; different results (on most runs)
> 32 bit on Snow Leopard: R CMD check passes; different results (on some runs).
> 64 bit on Snow Leopard: R CMD check passes; identical results
>
> For SVN version of Matrix with CRAN lme4:
>
> 32 bit on Snow Leopard: different results (on all runs).
> 64 bit on Snow Leopard: different results (on all runs)
>
> For SVN version of Matrix with SVN lme4a:
>
> 32 bit on Snow Leopard: different results (on all runs).
> 64 bit on Snow Leopard: identical results
>
> I couldn't reproduce on Linux 32/64bit. Is it time to jump into valgrind to try and find the cause?
>
> Cheers,
> Daniel
>
>
>
> On 17/07/10 5:51 PM, John Maindonald wrote:

>> In principle, maybe a Snow Leopard version might be posted
>> as an alternative, if someone can provide one.  But I take it
>> that the issue is now a bit wider than tests that fail on Leopard
>> vs passing on Snow Leopard?
>>   

>
>


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