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