Python notes - date and time

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Various things have their own pages, see Category:Python. Some of the pages that collect various practical notes include:


Conversions

Some code I've copy-pasted more than once:


from seconds-since-unix-epoch

# to '''datetime object'''
datetime.datetime.fromtimestamp( value ) # int or float

from elapsed seconds

# to timedelta
td = datetime.timedelta(seconds=int_or_float)

from timedelta

### 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

from datetime

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
# simplest, but you have to install/include it
dateutil.parser.parse(s)
 
# quick and dirty independent hack
def iso8601_dt_hack(s):
    ''' 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 instead. '''
    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

dateutil is a nice library for structured-but-not-quite-as-standardized strings (and various date-based logic you may not want to do yourself).

You probably want to just use dateutil.parser.parse()

For example:

>>> 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, though 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. [1]

from apache log time

Apache uses date-time-with-timezone format like:

29/Nov/2013:14:21:20 +0100

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)

Unsorted

See also: