Error creating R data.table with date-time POSIXlt

Formatting response from Blue Magister's comment (thanks so much), data.table does not support POSIXlt data types for performance reason -- see cast string to IDateTime as suggested as possible duplicate.

So the way to go is to cast time as ITime (type provided by data.table) or date-time (or date only) as POSIXct, depending upon whether date info is important or not:

> mdt <- data.table(id=1:3, d=as.ITime(strptime(c("06:02:36", "06:02:48", "07:03:12"), "%H:%M:%S")))
> print(mdt)
   id        d
1:  1 06:02:36
2:  2 06:02:48
3:  3 07:03:12
> mdt <- data.table(id=1:3, d=as.POSIXct(strptime(c("06:02:36", "06:02:48", "07:03:12"), "%H:%M:%S")))
> print(mdt)
   id                   d
1:  1 2014-01-31 06:02:36
2:  2 2014-01-31 06:02:48
3:  3 2014-01-31 07:03:12

As an extra note in case someone can benefit from it, I wanted to create date & time from my input data with date & time in separate fields. I found it useful to learn (see ?ITime) that one can add time ITime to date-time POSIXct and get a date-time POSIXct as follows:

> mdt <- as.POSIXct("2014-01-31") + as.ITime("06:02:36")
> print(mdt)
[1] "2014-01-31 06:02:36 EST"
> class(mdt)
[1] "POSIXct" "POSIXt"