[obspy-users] UTCDateTime and leap seconds?
krischer at geophysik.uni-muenchen.de
Fri Mar 17 15:52:45 CET 2017
currently UTCDateTime is not aware of leap seconds. We have some
discussions online and the current plan is to enable it for time
difference calculations, e.g
time_a - time_b
If there is a leap-second in-between it will be reflected in that. Same
when adding a time and a duration.
Your example contains a leap second time which we will likely not handle
because neither our underlying time representation nor Python can
actually deal with these "60-second" times (there were some internal
discussions on the python dev mailing list but if I remember correctly
they deemed the problem not serious enough to deal with it). We'd
probably just raise an error in these cases.
It might be possible to add a flag "is_leapsecond" to the UTCDateTime
object and than gracefully handle these cases but this will likely bring
along quite some additional complexity.
It is indeed a bit problematic but it only matters for time difference
that have one or more leap seconds in between so the actual damage is
likely limited. But we should somehow find a proper way to deal with it.
Please join the discussion on Github if you have some more ideas:
On 17/03/2017 15:26, Christian Weidle wrote:
> as I ran across an issue on leap seconds elsewhere, I wondered if/how
> they are dealt with in the UTCDateTime object.
> In : t0 = UTCDateTime(2017,1,1)
> In : t0 -1
> Out: 2016-12-31T23:59:59.000000Z
> ... while in principle t0-1 should be 2016-12-31T23:59:60.000000Z due
> to the recent leapsecond.
> With 27 leapseconds since 1972 this might be a problem in some use cases.
> Has this been considered somewhere in the development?
> obspy-users mailing list
> obspy-users at lists.swapbytes.de
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