[datatable-help] assigning POSIXlt object to a data.table column

[Matthew Dowle]

Hi,

It's burried in the Notes section of ?data.table :

  " POSIXlt is not supported as a column type because it uses 40 bytes 
to store a single datetime. Unexpected errors may occur if you manage to 
create a column of type POSIXlt. Please see NEWS for 1.6.3, and 
IDateTime instead. IDateTime has methods to convert to and from POSIXlt. 
"

The no-support for POSIXlt is set in stone,  but the advice there to 
use IDateTime may not be the best. Bascially - anything but POSIXlt!

Btw, please don't assign to DT columns using DT$test<-.  See ?":=".

Matthew

On 22.04.2013 13:27, Erik Iverson wrote:
> Hello,
>
> Hope all is well with everyone, just wondering if this is a 
> data.table
> bug or a bug in my understanding:
>
>> DT <- data.table(x = 1)
>> DT$test <- as.POSIXlt(Sys.Date())
> Warning message:
> In `[<-.data.table`(x, j = name, value = value) :
>   Supplied 9 items to be assigned to 1 items of column 'test' (8 
> unused)
>
> Thanks!
> --Erik
>
> sessionInfo()
> R version 3.0.0 (2013-04-03)
> Platform: x86_64-unknown-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=C                 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] wordcloud_2.4      RColorBrewer_1.0-5 Rcpp_0.10.3        
> tm_0.5-8.3
> [5] ggplot2_0.9.3.1    zoo_1.7-9          data.table_1.8.8   
> XML_3.96-1.1
>
> loaded via a namespace (and not attached):
>  [1] colorspace_1.2-2 compiler_3.0.0   dichromat_2.0-0  digest_0.6.3
>  [5] grid_3.0.0       gtable_0.1.2     labeling_0.1     
> lattice_0.20-15
>  [9] MASS_7.3-26      munsell_0.4      plyr_1.8         proto_0.3-10
> [13] reshape2_1.2.2   scales_0.2.3     slam_0.1-28      stringr_0.6.2
> [17] tools_3.0.0
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