Python notes - date and time
| Syntaxish: syntax and language · importing, modules, packages · iterable stuff · concurrency
date and time
Some code I've copy-pasted more than once:
# to '''datetime object''' datetime.datetime.fromtimestamp( value ) # int or float
from elapsed seconds
# to timedelta td = datetime.timedelta(seconds=int_or_float)
### to time difference in seconds # py>=2.7 added seconds = timedelta.total_seconds() # py2.6 and earlier: seconds = (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10**6) / 10**6
WARNING: discards timezone.
# to ISO8601-like string isostr = dtval.strftime('%Y-%m-%dT%H:%M:%S%z') ### to unix timestamp (float) # some variations. If you care about microseconds: time.mktime(dtval.timetuple()) + (1e-6)*dtval.microsecond
from seconds-since-epoch (a.k.a. unix time, a.k.a. "what time.time() gives")
# to datetime dt = datetime.datetime.fromtimestamp(int_or_float) # to ISO8601 style string isostr = datetime.datetime.fromtimestamp(int_or_float).strftime('%Y-%m-%dT%H:%M:%S%z')
From ISO8601 string
### to datetime # easier and better than the below, but you have to install/include it dateutil.parser.parse(s) # quick and dirty independent hack def iso8601_dt_hack(s): ''' strptime is a "parse this string according to this date string" thing. The below strips timezone (if present) to make it easier to deal with but only sensible within the same timezone. If you want to deal with timezones correctly, or want to deal with the compact format at all, then you probably want to use dateutil. ''' d, t = s.split('T',1) if '-' in t: t=t[:t.index('-')] if 'Z' in t: t=t[:t.index('Z')] if '+' in t: t=t[:t.index('+')] if '.' in t: # also chops off the above. Separate because I could add fractional-sec handling later t=t[:t.index('.')] return datetime.datetime.strptime('%sT%s'%(d,t), "%Y-%m-%dT%H:%M:%S")
from standardish strings
You can parse given a specific format like:
dt = datetime.datetime.strptime( dt_txt, "%Y-%m-%d-%H-%M-%S")
When you may get structured-but-not-necessarily-standard strings, or varied free-form strings, then dateutil is nice, as a fallback or in general. (it also has various date-based logic you may not want to do yourself).
You probably want the dateutil.parser.parse() function
>>> dateutil.parser.parse('2015-06-26 23:00:41') datetime.datetime(2015, 6, 26, 23, 0, 41) >>> dateutil.parser.parse("Thu Sep 25 2003") datetime.datetime(2003, 9, 25, 0, 0)
It seems to match on known patterns so will will work on many commonish/standardish things.
It doesn't like seeing parts it doesn't understand, apparently being cautious. It will be more permissive with fuzzy=True (e.g. it groks apache's date format only with fuzziness, apparently because of the unexpected : between date and time)
On ambiguous dates like 02-04-2012 you may have to guide it, see e.g. 
from apache log time
Apache uses date-time-with-timezone format like:
dateutil.parser.parse with fuzzy=True will deal.
You can do with with a dozen lines of string manipulation, which may be slightly faster(verify) (TODO: add that)