[Numpy-discussion] Proposal: add the timestamp64 type (Noam Yorav-Raphael)

[Stefano Miccoli]

On 11 Nov 2020, at 18:00, numpy-discussion-request at python.org<mailto:numpy-discussion-request at python.org> wrote:

I propose to add a new type called "timestamp64". It will be a pure timestamp, meaning that it represents a moment in time (as seconds/ms/us/ns since the epoch), without any timezone information.

Sorry, but I really don see the usefulness for another time stamping format based on POSIX time. Indeed POSIX time is based on a naive approximation of UTC and is ambiguous across leap seconds. Quoting from Wikipedia <https://en.wikipedia.org/wiki/Unix_time#Leap_seconds>

The Unix time number 1483142400 is thus ambiguous: it can refer either to start of the leap second (2016-12-31 23:59:60) or the end of it, one second later (2017-01-01 00:00:00). In the theoretical case when a negative leap second occurs, no ambiguity is caused, but instead there is a range of Unix time numbers that do not refer to any point in UTC time at all.

Precision time stamping is quite a complex task: you can use UTC, TAI, GPS, just to mention the most used timescales. And how do you deal with timestamps in the past, when timekeeping was based on earth rotation, and not atomic clocks ticking at (approximately) 1 SI-second frequency?

In my opinion time-stamping should be application dependent, and I doubt that the new “timestamp64” could be beneficial to the numpy community.

Best regards,

Stefano
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