numpytimebuilder 0.4.1

A library for using the NumPy datetime API with aniso8601

NumPyTimeBuilder

aniso8601 builder for NumPy datetimes

Features

• Provides NumPyTimeBuilder compatible with aniso8601

• Returns datetime64 and timedelta64 NumPy types

Installation

The recommended installation method is to use pip:

$ pip install numpytimebuilder

Alternatively, you can download the source (git repository hosted at Bitbucket) and install directly:

$ python setup.py install

Use

Parsing datetimes

To parse a typical ISO 8601 datetime string:

>>> import aniso8601
>>> from numpytimebuilder import NumPyTimeBuilder
>>> aniso8601.parse_datetime('1977-06-10T12:00:00', builder=NumPyTimeBuilder)
numpy.datetime64('1977-06-10T12:00:00')

Alternative delimiters can be specified, for example, a space:

>>> aniso8601.parse_datetime('1977-06-10 12:00:00', delimiter=' ', builder=NumPyTimeBuilder)
numpy.datetime64('1977-06-10T12:00:00')

Since the NumPy datetime64 implementaton only supports naive datetimes, timezones are explicitly not supported:

>>> aniso8601.parse_datetime('1977-06-10T12:00:00Z', builder=NumPyTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/nielsenb/Jetfuse/numpytimebuilder/python2/lib/python2.7/site-packages/aniso8601/time.py", line 131, in parse_datetime
    return builder.build_datetime(datepart, timepart)
  File "numpytimebuilder/__init__.py", line 37, in build_datetime
    raise NotImplementedError('Timezones are not supported by numpy '
NotImplementedError: Timezones are not supported by numpy datetime64 type.
>>> aniso8601.parse_datetime('1979-06-05T08:00:00-08:00', builder=NumPyTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/nielsenb/Jetfuse/numpytimebuilder/python2/lib/python2.7/site-packages/aniso8601/time.py", line 131, in parse_datetime
    return builder.build_datetime(datepart, timepart)
  File "numpytimebuilder/__init__.py", line 37, in build_datetime
    raise NotImplementedError('Timezones are not supported by numpy '
NotImplementedError: Timezones are not supported by numpy datetime64 type

Leap seconds are not currently supported by the NumPy datetime64 implementation, so leap seconds are explicitly not supported:

>>> aniso8601.parse_datetime('2018-03-06T23:59:60', builder=NumPyTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/nielsenb/Jetfuse/numpytimebuilder/python2/lib/python2.7/site-packages/aniso8601/time.py", line 131, in parse_datetime
    return builder.build_datetime(datepart, timepart)
  File "numpytimebuilder/__init__.py", line 120, in build_datetime
    raise LeapSecondError('Leap seconds are not supported.')
aniso8601.exceptions.LeapSecondError: Leap seconds are not supported.

Parsing dates

To parse a date represented in an ISO 8601 string:

>>> import aniso8601
>>> from numpytimebuilder import NumPyTimeBuilder
>>> aniso8601.parse_date('1984-04-23', builder=NumPyTimeBuilder)
numpy.datetime64('1984-04-23')

Basic format is supported as well:

>>> aniso8601.parse_date('19840423', builder=NumPyTimeBuilder)
numpy.datetime64('1984-04-23')

To parse a date using the ISO 8601 week date format:

>>> aniso8601.parse_date('1986-W38-1', builder=NumPyTimeBuilder)
numpy.datetime64('1986-09-15')

To parse an ISO 8601 ordinal date:

>>> aniso8601.parse_date('1988-132', builder=NumPyTimeBuilder)
numpy.datetime64('1988-05-11')

Parsing times

NumPy offers no time64 type, so parsing times is explicitly not supported:

>>> import aniso8601
>>> from numpytimebuilder import NumPyTimeBuilder
>>> aniso8601.parse_time('11:31:14', builder=NumPyTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/nielsenb/Jetfuse/numpytimebuilder/python2/lib/python2.7/site-packages/aniso8601/time.py", line 116, in parse_time
    return _RESOLUTION_MAP[get_time_resolution(timestr)](timestr, tz, builder)
  File "/home/nielsenb/Jetfuse/numpytimebuilder/python2/lib/python2.7/site-packages/aniso8601/time.py", line 165, in _parse_second_time
    return builder.build_time(hh=hourstr, mm=minutestr, ss=secondstr, tz=tz)
  File "numpytimebuilder/__init__.py", line 32, in build_time
    raise NotImplementedError('No compatible numpy time64 type.')
NotImplementedError: No compatible numpy time64 type.

Parsing durations

The NumPy timedelta64 type only supports a single component per delta, so durations are returned as a tuple of timedelta64 objects.

To parse a duration formatted as an ISO 8601 string:

>>> import aniso8601
>>> from numpytimebuilder import NumPyTimeBuilder
>>> aniso8601.parse_duration('P1Y2M3DT4H54M6S', builder=NumPyTimeBuilder)
(numpy.timedelta64(428,'D'), numpy.timedelta64(4,'h'), numpy.timedelta64(54,'m'), numpy.timedelta64(6,'s'), numpy.timedelta64(0,'ms'), numpy.timedelta64(0,'us'), numpy.timedelta64(0,'ns'), numpy.timedelta64(0,'ps'), numpy.timedelta64(0,'fs'), numpy.timedelta64(0,'as'))

Reduced accuracy is supported:

>>> aniso8601.parse_duration('P1Y', builder=NumPyTimeBuilder)
(numpy.timedelta64(365,'D'), numpy.timedelta64(0,'h'), numpy.timedelta64(0,'m'), numpy.timedelta64(0,'s'), numpy.timedelta64(0,'ms'), numpy.timedelta64(0,'us'), numpy.timedelta64(0,'ns'), numpy.timedelta64(0,'ps'), numpy.timedelta64(0,'fs'), numpy.timedelta64(0,'as'))

A decimal fraction is allowed on the lowest order element:

>>> aniso8601.parse_duration('P1YT3.5M', builder=NumPyTimeBuilder)
(numpy.timedelta64(365,'D'), numpy.timedelta64(0,'h'), numpy.timedelta64(3,'m'), numpy.timedelta64(30,'s'), numpy.timedelta64(0,'ms'), numpy.timedelta64(0,'us'), numpy.timedelta64(0,'ns'), numpy.timedelta64(0,'ps'), numpy.timedelta64(0,'fs'), numpy.timedelta64(0,'as'))

The decimal fraction can be specified with a comma instead of a full-stop:

>>> aniso8601.parse_duration('P1YT3,5M', builder=NumPyTimeBuilder)
(numpy.timedelta64(365,'D'), numpy.timedelta64(0,'h'), numpy.timedelta64(3,'m'), numpy.timedelta64(30,'s'), numpy.timedelta64(0,'ms'), numpy.timedelta64(0,'us'), numpy.timedelta64(0,'ns'), numpy.timedelta64(0,'ps'), numpy.timedelta64(0,'fs'), numpy.timedelta64(0,'as'))

Parsing a duration from a combined date and time is supported as well:

>>> aniso8601.parse_duration('P0001-01-02T01:30:5', builder=NumPyTimeBuilder)
(numpy.timedelta64(397,'D'), numpy.timedelta64(1,'h'), numpy.timedelta64(30,'m'), numpy.timedelta64(5,'s'), numpy.timedelta64(0,'ms'), numpy.timedelta64(0,'us'), numpy.timedelta64(0,'ns'), numpy.timedelta64(0,'ps'), numpy.timedelta64(0,'fs'), numpy.timedelta64(0,'as'))

The above treat years as 365 days and months as 30 days. Calendar level accuracy is not supported. Fractional years and months are supported accordingly:

>>> aniso8601.parse_duration('P2.1Y', builder=NumPyTimeBuilder)
(numpy.timedelta64(766,'D'), numpy.timedelta64(12,'h'), numpy.timedelta64(0,'m'), numpy.timedelta64(0,'s'), numpy.timedelta64(0,'ms'), numpy.timedelta64(0,'us'), numpy.timedelta64(0,'ns'), numpy.timedelta64(0,'ps'), numpy.timedelta64(0,'fs'), numpy.timedelta64(0,'as'))
>>> aniso8601.parse_duration('P1Y0.5M', builder=NumPyTimeBuilder)
(numpy.timedelta64(380,'D'), numpy.timedelta64(0,'h'), numpy.timedelta64(0,'m'), numpy.timedelta64(0,'s'), numpy.timedelta64(0,'ms'), numpy.timedelta64(0,'us'), numpy.timedelta64(0,'ns'), numpy.timedelta64(0,'ps'), numpy.timedelta64(0,'fs'), numpy.timedelta64(0,'as'))

Applying durations

The apply_duration helper function is provided for applying duration tuples to a datetime64 object. It takes a datetime64 (from parse_datetime), a duration tuple (from parse_duration), and a Python operator to be applied:

>>> import aniso8601
>>> import operator
>>> from numpytimebuilder import NumPyTimeBuilder
>>> from numpytimebuilder.util import apply_duration
>>> datetime = aniso8601.parse_datetime('1977-06-10T12:00:00', builder=NumPyTimeBuilder)
>>> duration = aniso8601.parse_duration('P3Y2M1DT1H2M3S', builder=NumPyTimeBuilder)
>>> apply_duration(datetime, duration, operator.add)
numpy.datetime64('1980-08-09T13:02:03')

Keep in mind the span of representable datetimes decreases as the resolution increases! See the NumPy Datetime Units documentation for more information.

Parsing intervals

To parse an interval specified by a start and end:

>>> import aniso8601
>>> from numpytimebuilder import NumPyTimeBuilder
>>> aniso8601.parse_interval('2007-03-01T13:00:00/2008-05-11T15:30:00')
(numpy.datetime64('2007-03-01T13:00:00'), numpy.datetime64('2008-05-11T15:30:00'))

Intervals specified by a start time and a duration are supported:

>>> aniso8601.parse_interval('2007-03-01T13:00:00/P1Y2M10DT2H30M', builder=NumPyTimeBuilder)
(numpy.datetime64('2007-03-01T13:00:00'), numpy.datetime64('2008-05-09T15:30:00'))

A duration can also be specified by a duration and end time:

>>> aniso8601.parse_interval('P1M/1981-04-05', builder=NumPyTimeBuilder)
(numpy.datetime64('1981-04-05'), numpy.datetime64('1981-03-06'))

Notice that the result of the above parse is not in order from earliest to latest. If sorted intervals are required, simply use the sorted keyword as shown below:

>>> sorted(aniso8601.parse_interval('P1M/1981-04-05', builder=NumPyTimeBuilder))
[numpy.datetime64('1981-03-06'), numpy.datetime64('1981-04-05')]

The end of an interval is returned as a datetime when required to maintain the resolution specified by a duration, even if the duration start is given as a date:

>>> aniso8601.parse_interval('2014-11-12/PT4H54M6.5S', builder=NumPyTimeBuilder)
(numpy.datetime64('2014-11-12'), numpy.datetime64('2014-11-12T04:54:06.500'))
>>> aniso8601.parse_interval('2007-03-01/P1.5D', builder=NumPyTimeBuilder)
(numpy.datetime64('2007-03-01'), numpy.datetime64('2007-03-02T12:00:00'))

Repeating intervals are supported as well, and return a generator:

>>> aniso8601.parse_repeating_interval('R3/1981-04-05/P1D', builder=NumPyTimeBuilder)
<generator object _date_generator at 0x7fd76fe9abe0>
>>> list(aniso8601.parse_repeating_interval('R3/1981-04-05/P1D', builder=NumPyTimeBuilder))
[numpy.datetime64('1981-04-05'), numpy.datetime64('1981-04-06'), numpy.datetime64('1981-04-07')]

Repeating intervals are allowed to go in the reverse direction:

>>> list(aniso8601.parse_repeating_interval('R2/PT1H2M/1980-03-05T01:01:00', builder=NumPyTimeBuilder))
[numpy.datetime64('1980-03-05T01:01:00'), numpy.datetime64('1980-03-04T23:59:00')]

Unbounded intervals are also allowed (Python 2):

>>> result = aniso8601.parse_repeating_interval('R/PT1H2M/1980-03-05T01:01:00', builder=NumPyTimeBuilder)
>>> result.next()
numpy.datetime64('1980-03-05T01:01:00')
>>> result.next()
numpy.datetime64('1980-03-04T23:59:00')

or for Python 3:

>>> result = aniso8601.parse_repeating_interval('R/PT1H2M/1980-03-05T01:01:00', builder=NumPyTimeBuilder)
>>> next(result)
numpy.datetime64('1980-03-05T01:01:00')
>>> next(result)
numpy.datetime64('1980-03-04T23:59:00')

The above treat years as 365 days and months as 30 days. Calendar level accuracy is not supported. Fractional months and years are supported accordingly:

>>> aniso8601.parse_interval('P1.1Y/2001-02-28', builder=NumPyTimeBuilder)
(numpy.datetime64('2001-02-28'), numpy.datetime64('2000-01-24'))
>>> aniso8601.parse_interval('2001-02-28/P1Y2.5M', builder=NumPyTimeBuilder)
(numpy.datetime64('2001-02-28'), numpy.datetime64('2002-05-14'))

Development

Setup

It is recommended to develop using a virtualenv.

Configure the development environment and pull in any required dependencies:

$ python setup.py develop

Tests

Tests can be run using the unittest testing framework:

$ python -m unittest discover numpytimebuilder

Contributing

numpytimebuilder is an open source project hosted on Bitbucket.

Any and all bugs are welcome on our issue tracker.

References

• NumPy datetimes and timedeltas

• aniso8601 and sub-microsecond precision