[datatable-help] possible bug when running setkey on POSIXct column

statquant statquant at outlook.com
Fri Jan 18 16:06:20 CET 2013


It is definitely as.POSIXct (but in conjunction with data.table?) that
causes problems, as replacing it by as.Date, in the previous lines of code,
leads to correct result.
Cheers

2013/1/18 statquant <statquant at outlook.com>

> Hello I might have found a bug.
> I really cannot explain the following (please be indulgent as I narrowed
> the most I could).
>
> library(data.table)
> DT = data.table(X=as.POSIXct( c(rep("15DEC2008:00:00:00",10)
> ,"15DEC2008:00:00:00",rep("17DEC2008:00:00:00",2)),
> format="%d%b%Y:%H:%M:%S"),Y=c(1534,61,74,518,519,1519,1520,
> 1524,3127,29250,30609,43,7853))
> setkey(DT,X,Y)
>
> #Here is what I see after the sort
>
> DT
>              X     Y
>  1: 2008-12-15  *1534*
>  2: 2008-12-15    61
>  3: 2008-12-15    74
>  4: 2008-12-15   518
>  5: 2008-12-15   519
>  6: 2008-12-15  1519
>  7: 2008-12-15  1520
>  8: 2008-12-15  1524
>  9: 2008-12-15  3127
> 10: 2008-12-15 29250
> 11: 2008-12-15 30609
> 12: 2008-12-17    43
> 13: 2008-12-17  7853
>
> #I thought that it was a POSIXct problem but if I can get the correct
> answer like this:
>
> DT[order(X,Y),]
>              X     Y
>  1: 2008-12-15    61
>  2: 2008-12-15    62
>  3: 2008-12-15    74
>  4: 2008-12-15   518
>  5: 2008-12-15   519
>  6: 2008-12-15  1519
>  7: 2008-12-15  1520
>  8: 2008-12-15  1524
>  9: 2008-12-15  3127
> 10: 2008-12-15 29250
> 11: 2008-12-15 30609
> 12: 2008-12-17    43
> 13: 2008-12-17  7853
>
> #Here is my session (just launched it)
>
> R> sessionInfo()
> R version 2.15.2 (2012-10-26)
> Platform: x86_64-pc-linux-gnu (64-bit)
>
> locale:
>  [1] LC_CTYPE=en_GB.UTF-8       LC_NUMERIC=C
> LC_TIME=C
>  [4] LC_COLLATE=en_GB.UTF-8     LC_MONETARY=fr_FR.UTF-8
> LC_MESSAGES=en_GB.UTF-8
>  [7] LC_PAPER=C                 LC_NAME=C
> LC_ADDRESS=C
> [10] LC_TELEPHONE=C             LC_MEASUREMENT=fr_FR.UTF-8
> LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats     graphics  grDevices datasets  utils     methods   base
>
> other attached packages:
> [1] data.table_1.8.7 inline_0.3.10    Rcpp_0.10.2      vimcom_0.9-5
> setwidth_1.0-2
> [6] colorout_0.9-9
>
>
>
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