[datatable-help] What is going on with R 3.1 ?

[Steve Lianoglou]

Hi,

On Thu, Apr 17, 2014 at 10:15 AM, Michele <carrieromichele at gmail.com> wrote:
> If I try to copy() the tables to re-create the pointers all the tables get
> the same one, always ending in 788 (opening another R session I get the same
> result, same pointers accross the table, ending in 788):
>
>> dt <- readRDS("dt.RDS")
>> dt1 <- readRDS("dt1.RDS")
>> dput(copy(dt))
> structure(list(id = 1:5, var = c(-0.626453810742332, 0.183643324222082,
> -0.835628612410047, 1.59528080213779, NA)), .Names = c("id",
> "var"), row.names = c(NA, -5L), class = c("data.table", "data.frame"
> ), .internal.selfref = <pointer: 0x00000000003e0788>)
>> dput(copy(dt1))
> structure(list(id = 1:10, var2 = c(9.56605515060971, 9.83445938796679,
> 9.14481066107107, 10.5308762543727, NA, NA, 9.45024506381369,
> 10.0544601882071, 10.7019565371199, 9.60325830155958), var3 =
> c(99.6542887323489,
> 100.659231456233, 100.282028460177, 101.423474800432, 98.4134121985332,
> NA, 98.0406472259105, 100.253194731594, 100.759881151841, 99.7930775536395
> )), .Names = c("id", "var2", "var3"), row.names = c(NA, -10L), class =
> c("data.table",
> "data.frame"), sorted = "id", .internal.selfref = <pointer:
> 0x00000000003e0788>)

Is this actually causing a problem for you somewhere?

For instance, if you modify-by-reference "dt", like `dt[, z := 1]`, is
`dt1` modified as well (it shouldn't be)?

Let's try another experiment. Forget loading from an *.rds and just
create a brand new data.table and look at its .internal.selfref:

R> a <- data.table(a=1:10)
R> b <- data.table(a=1:10)
R> attributes(a)$.internal.selfref
R> attributes(b)$.internal.selfref

What do you see?

Also, your initial post referenced two errors that both mentioned
something about a missing logical value ("missing value where
TRUE/FALSE needed"), but it's not clear what triggered the error. Have
you been able to reproduce this?

Next time this happens, can you call "traceback()" and provide the
stack trace here?

Also, your original post also said:

>  It's very unstable and I get different results time to time

What is very unstable? And what results are different? What exact
operations are you performing that are producing different results
when you run them more than once?

If you could provide a more precise explanation of what the problem is
you are actually encountering via some piece of code that is producing
the unexpected behavior you are observing, that would be most helpful.

Thanks,
-steve

-- 
Steve Lianoglou
Computational Biologist
Genentech