[datatable-help] Non-integer key?

[Chris Neff]

Have you seen the ITime class (also IDate and IDateTime)? Meant for
this purpose.

On 14 August 2011 21:44, Leon Baum <leonbaum2 at gmail.com> wrote:
>
> Hello,
>
> I understand the performance reasons for requiring the key to be of
> integer type, but I often would like to use data.table's joining and
> grouping features with millisecond POSIXct timestamps.
>
> One workaround is to convert the timestamps to an integer representing
> the milliseconds since the first timestamp, but for time ranges of
> larger than a few weeks, the number of milliseconds is larger than what
> can be stored in a 32-bit integer.
>
> I see two possible solutions:
>
> 1. Store the integer milliseconds as numeric type, which allows 64-bit
> integers to be stored exactly. This solution would simply require an
> option for data.table to assume that a numeric type is actually storing
> integer values.
>
> 2. Add a second, slower, sorting algorithm to data.table that could
> handle non-integer values. This solution would allow POSIXct types to be
> used directly by data.table.
>
> Are either of these solutions possible and reasonable? Or is there some
> workaround I'm missing to be able to use larger-than-32-bit integers as
> keys?
>
> -Leon
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