[datatable-help] Key dropped when DT[, list(a, b)]

[Eduard Antonyan]

This was fixed relatively recently in revision 999, so try updating your
build.


On Fri, Nov 22, 2013 at 10:33 AM, daniel.krizian
<daniel.krizian at gmail.com>wrote:

> Hello Steve and thanks for your reply. I am running data.table_1.8.11
>
> Full details below:
>
> > sessionInfo()
> R version 3.0.2 (2013-09-25)
> Platform: x86_64-w64-mingw32/x64 (64-bit)
>
> locale:
> [1] LC_COLLATE=English_United Kingdom.1252  LC_CTYPE=English_United
> Kingdom.1252
> [3] LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C
>
> [5] LC_TIME=English_United Kingdom.1252
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
>  [1] timeDate_3010.98           data.table_1.8.11
>  quantstrat_0.7.8
>  [4] foreach_1.4.1              blotter_0.8.15
> PerformanceAnalytics_1.1.1
>  [7] FinancialInstrument_1.1    quantmod_0.4-0             Defaults_1.1-1
>
> [10] TTR_0.22-0                 xts_0.9-5                  zoo_1.7-10
>
>
> loaded via a namespace (and not attached):
> [1] codetools_0.2-8 grid_3.0.2      iterators_1.0.6 lattice_0.20-23
> plyr_1.8
> [6] reshape2_1.2.2  stringr_0.6.2   tools_3.0.2
>
>
> On Fri, Nov 22, 2013 at 2:50 PM, Steve Lianoglou-2 [via R] <[hidden email]<http://user/SendEmail.jtp?type=node&node=4680970&i=0>
> > wrote:
>
>> Hi Daniel,
>>
>> On Fri, Nov 22, 2013 at 6:15 AM, daniel.krizian
>> <[hidden email] <http://user/SendEmail.jtp?type=node&node=4680967&i=0>>
>> wrote:
>> > Hello, I have:
>> >
>> > DT <- data.table(a=1:10, b=1:10,c=1:10, key=c("a","b"))
>> > key(DT) # [1] "a" "b"
>> > key(DT[,list(a,b)]) # NULL
>> >
>> > Note that DT loses its key when I select a subset of columns like
>> above.
>> >
>> > Is this a (known) bug/ expected result?
>>
>> The key is retained for me when I run your code:
>>
>> R> key(DT[,list(a,b)])
>> [1] "a" "b"
>>
>> What version of data.table are you using?
>>
>> -steve
>>
>> --
>> Steve Lianoglou
>> Computational Biologist
>> Genentech
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>
>
> --
> *____________________________*
> *Daniel Krizian, CFA, CAIA*
> T: +44 74 5372 1101
> M: [hidden email] <http://user/SendEmail.jtp?type=node&node=4680970&i=1>
> uk.linkedin.com/in/danielkrizian
> B: quantology.wordpress.com
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