[datatable-help] .SD is locked

[G See]

Thanks guys.  Bug report filed.

On Sun, Nov 17, 2013 at 5:43 PM, Arunkumar Srinivasan
<aragorn168b at gmail.com> wrote:
> Gsee, just adding the line:
>
> if (identical(jval, SDenv$.SD)) jval = copy(jval)
>
> before `return(jval)` seems to fix this (and all tests also complete without
> any issues). If you're in a hurry for fix, you could just add it for now.
>
> I'll test it again later and commit with other changes I've staged locally.
> It'd still be nice to file this as a bug so that it could be tracked.
>
> Best,
> Arun
>
> On Monday, November 18, 2013 at 12:29 AM, Arunkumar Srinivasan wrote:
>
> Hm, nice catch! In this special case, the value returned is from this code:
>
> jval = eval(jsub, SDenv, parent.frame())
>
> Since `jsub = .SD`, this evaluates to .SD ('s value). However, since `jval`
> remains untouched, a copy is not made (I think). This can be seen with a
> `tracemem` statement:
>
> x <- as.data.table(BOD)
> xx <- x[, {print(tracemem(.SD)); .SD}, .SDcols="Time"]
> [1] "<0x7fa4e9a518f0>"
> tracemem(xx)
> [1] "<0x7fa4e9a518f0>"
>
> Basically `xx` is `.SD` and therefore is 'locked'. I guess a fix would be to
> check this and make a copy on return. Not sure.
>
> Arun
>
> On Monday, November 18, 2013 at 12:11 AM, Michael Nelson wrote:
>
> I don't believe this is to be expected.
>
> A bug report should be filed (it is present in 1.8.10 on CRAN as well)
>
> .SD is locked so you can't "mess" with it within a call to `[.data.table`,
> but this "locked" status should not be retained following the completion of
> that call
>
>
> ________________________________________
> From: datatable-help-bounces at lists.r-forge.r-project.org
> [datatable-help-bounces at lists.r-forge.r-project.org] on behalf of G See
> [gsee000 at gmail.com]
> Sent: Monday, 18 November 2013 9:32 AM
> To: datatable-help at lists.r-forge.r-project.org
> Subject: [datatable-help] .SD is locked
>
> Hi,
>
> Is the following error expected?
>
> library(data.table)
>
> data.table 1.8.11 For help type: help("data.table")
>
> x <- as.data.table(BOD)
> xx <- x[, .SD, .SDcols="Time"]
> xx[, Time:=as.numeric(Time)]
>
> Error in `[.data.table`(xx, , `:=`(Time, as.numeric(Time))) :
> .SD is locked. Using := in .SD's j is reserved for possible future
> use; a tortuously flexible way to modify by group. Use := in j
> directly to modify by group by reference.
>
> sessionInfo()
>
> R version 3.0.2 (2013-09-25)
> Platform: x86_64-pc-linux-gnu (64-bit)
>
> locale:
> [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
> [3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
> [5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
> [7] LC_PAPER=en_US.UTF-8 LC_NAME=C
> [9] LC_ADDRESS=C LC_TELEPHONE=C
> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats graphics grDevices utils datasets methods base
>
> other attached packages:
> [1] data.table_1.8.11
>
> loaded via a namespace (and not attached):
> [1] plyr_1.8 reshape2_1.2.2 stringr_0.6.2
>
>
> Thanks,
> Garrett
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