numpy.datetime_as_string(arr, unit=None, timezone='naive', casting='same_kind')

Convert an array of datetimes into an array of strings.

arr : array_like of datetime64

The array of UTC timestamps to format.

unit : str

One of None, ‘auto’, or a datetime unit.

timezone : {‘naive’, ‘UTC’, ‘local’} or tzinfo

Timezone information to use when displaying the datetime. If ‘UTC’, end with a Z to indicate UTC time. If ‘local’, convert to the local timezone first, and suffix with a +-#### timezone offset. If a tzinfo object, then do as with ‘local’, but use the specified timezone.

casting : {‘no’, ‘equiv’, ‘safe’, ‘same_kind’, ‘unsafe’}

Casting to allow when changing between datetime units.

str_arr : ndarray

An array of strings the same shape as arr.


>>> d = np.arange('2002-10-27T04:30', 4*60, 60, dtype='M8[m]')
>>> d
array(['2002-10-27T04:30', '2002-10-27T05:30', '2002-10-27T06:30',
       '2002-10-27T07:30'], dtype='datetime64[m]')

Setting the timezone to UTC shows the same information, but with a Z suffix

>>> np.datetime_as_string(d, timezone='UTC')
array(['2002-10-27T04:30Z', '2002-10-27T05:30Z', '2002-10-27T06:30Z',
       '2002-10-27T07:30Z'], dtype='<U35')

Note that we picked datetimes that cross a DST boundary. Passing in a pytz timezone object will print the appropriate offset

>>> np.datetime_as_string(d, timezone=pytz.timezone('US/Eastern'))
array(['2002-10-27T00:30-0400', '2002-10-27T01:30-0400',
       '2002-10-27T01:30-0500', '2002-10-27T02:30-0500'], dtype='<U39')

Passing in a unit will change the precision

>>> np.datetime_as_string(d, unit='h')
array(['2002-10-27T04', '2002-10-27T05', '2002-10-27T06', '2002-10-27T07'],
>>> np.datetime_as_string(d, unit='s')
array(['2002-10-27T04:30:00', '2002-10-27T05:30:00', '2002-10-27T06:30:00',
       '2002-10-27T07:30:00'], dtype='<U38')

‘casting’ can be used to specify whether precision can be changed

>>> np.datetime_as_string(d, unit='h', casting='safe')
TypeError: Cannot create a datetime string as units 'h' from a NumPy
datetime with units 'm' according to the rule 'safe'

Previous topic

Datetime Support Functions

Next topic