[Numpy-discussion] fixing up datetime

Mark Wiebe mwwiebe@gmail....
Wed Jun 1 16:16:06 CDT 2011

On Wed, Jun 1, 2011 at 3:52 PM, Charles R Harris

> <snip>
> Just a quick comment, as this really needs more thought, but time is a bag
> of worms.

Certainly a bag of worms, I agree.

> Trying to represent some standard -- say seconds at the solar system
> barycenter to account for general relativity -- is something that I think is
> too complicated and specialized to put into numpy.

Good support for units and delta times is very useful,

This part works fairly well now, except for some questions like what should
datetime("2011-01-30", "D") + timedelta(1, "M") produce. Maybe "2011-02-28",
or "2011-03-02"?

> but parsing dates and times

I've implemented an almost-ISO 8601 date-time parser.  I had to deviate a
bit to support years outside the little 10000-year window we use. I think
supporting more formats could be handled by writing a function which takes
its date format and outputs ISO 8601 format to feed numpy.

> and handling timezones, daylight savings,

The only timezone to handle is "local", which it looks like standard C has a
rich enough API for this to be ok.

> leap seconds,

This one can be mitigated by referencing TAI or GPS time, I think. POSIX
time looks like a can of worms though.

> business days,

I think Enthought has some interest in a decent business day functionality.
Some feedback from people doing time series and financial modeling would
help clarify this though. This link may provide some context:



> etc., is probably best served by addon packages specialized to an area of
> interest. Just my $.02
> Chuck
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