mktime, how to handle dates before 01-01-1970 ?

M.-A. Lemburg mal at egenix.com
Wed Oct 7 14:13:08 CEST 2009


Christian Heimes wrote:
> Ben Finney wrote:
>> If you're committed to changing the epoch anyway, I would recommend
>> using <URL:http://en.wikipedia.org/wiki/Astronomical_year_numbering>
>> (epoch at 4004 BCE) since it is widely used to unify dates referring to
>> human history.
> 
> I prefer JDN or MJD (http://en.wikipedia.org/wiki/JDN) for dates long
> before or after the unix epoch. The conversion from JDN as float to a
> datetime object is trivial.

FWIW, mxDateTime can help you with all of those:

>>> import mx.DateTime
>>> mx.DateTime.DateTimeFrom('1.1.4004 BCE')
<mx.DateTime.DateTime object for '-4003-01-01 00:00:00.00' at 2b534a46a2f0>
>>> mx.DateTime.DateTimeFrom('1.1.4004 BCE').jdn
258994.5
>>> mx.DateTime.DateTimeFromJDN(258994.5)
<mx.DateTime.DateTime object for '-4003-01-01 00:00:00.00' at 2b534aeb72f0>
>>> mx.DateTime.DateTimeFrom('1.1.4004 BCE').mjd
-2141006.0
>>> mx.DateTime.DateTimeFromMJD(-2141006.0)
<mx.DateTime.DateTime object for '-4003-01-01 00:00:00.00' at 2b534a46a2f0>

The supported date range is limited by the number of days
that fit into a C long. Should be enough for most use cases :-)

-- 
Marc-Andre Lemburg
eGenix.com

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