22

I have a timestamp in epoch time with nanoseconds - e.g. 1360287003083988472 nanoseconds since 1970-01-01.

The Python datetime objects and conversion methods only support up to millisecond precision.

Is there an easy way to convert this epoch time into human-readable time?

tripleee
  • 158,107
  • 27
  • 234
  • 292
victorhooi
  • 15,433
  • 21
  • 84
  • 112
  • 2
    @abarnert I don't think so. This question deals with converting a number to a human-readable string, whereas that one is trying to convert from a string to a `datetime` object. – ethguo Mar 27 '13 at 01:18
  • @ethg242: That question is sort of all over the place, but it comes down to the same thing: `datetime` doesn't handle nanoseconds, so you have to do the math/stringops yourself. Maybe it's fine to have one question about `strptime` and another about `strftime`. – abarnert Mar 27 '13 at 05:25
  • 1
    this is one turned out better than the duplicate – n611x007 Jun 13 '13 at 15:55
  • 1
    @abarnert Have you actually look at the answers on the other question? Lol. For some reason, naxa is right, the answers on this one turned out better, no idea why. – victorhooi Jun 14 '13 at 04:45
  • @victorhooi: Yes, sometimes dups do turn out better than the original. That means you shouldn't ignore a question just because it might be a dup (notice that one of the two answers here is mine), but it doesn't mean we shouldn't mark dups. – abarnert Jun 14 '13 at 18:55
  • Python's `datetime.datetime()` has microsecond support for the fractions and thus microsecond instead of millisecond precision. – Anthon Aug 20 '16 at 09:45

2 Answers2

38

First, convert it to a datetime object with second precision (floored, not rounded):

>>> from datetime import datetime
>>> dt = datetime.fromtimestamp(1360287003083988472 // 1000000000)
>>> dt
datetime.datetime(2013, 2, 7, 17, 30, 3)

Then to make it human-readable, use the strftime() method on the object you get back:

>>> s = dt.strftime('%Y-%m-%d %H:%M:%S')
>>> s
'2013-02-07 17:30:03'

Finally, add back in the nanosecond precision:

>>> s += '.' + str(int(1360287003083988472 % 1000000000)).zfill(9)
>>> s
'2013-02-07 17:30:03.083988472'
Andrew Clark
  • 192,132
  • 30
  • 260
  • 294
  • My problem here is that by using `1360287003083988472 // 1000000000`, you're at risk of loosing valuable information. One can get a human-readable format by using `datetime.fromtimestamp(1360287003083988472 / 1000000000)` instead. – r02 Feb 25 '21 at 12:32
12

Actually, Python's datetime methods handle microsecond precision, not millisecond:

>>> nanos = 1360287003083988472
>>> secs = nanos / 1e9
>>> dt = datetime.datetime.fromtimestamp(secs)
>>> dt.strftime('%Y-%m-%dT%H:%M:%S.%f')
'2013-02-07T17:30:03.083988'

But if you actually need nanoseconds, that still doesn't help. Your best bet is to write your own wrapper:

def format_my_nanos(nanos):
    dt = datetime.datetime.fromtimestamp(nanos / 1e9)
    return '{}{:03.0f}'.format(dt.strftime('%Y-%m-%dT%H:%M:%S.%f'), nanos % 1e3)

This gives me:

'2013-02-07T17:30:03.083988472'

Of course you could have done the same thing even if Python didn't do sub-second precision at all…

def format_my_nanos(nanos):
    dt = datetime.datetime.fromtimestamp(nanos / 1e9)
    return '{}.{:09.0f}'.format(dt.strftime('%Y-%m-%dT%H:%M:%S'), nanos % 1e9)
abarnert
  • 334,953
  • 41
  • 559
  • 636