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aniso8601 1.1.0

A library for parsing ISO 8601 strings.

Features

  • Pure Python implementation
  • Python 3 support
  • Logical behavior
  • UTC offset represented as fixed-offset tzinfo
  • dateutil.relativedelta available for calendar accuracy
  • No regular expressions

Installation

The recommended installation method is to use pip:

$ pip install aniso8601

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
>>> aniso8601.parse_datetime('1977-06-10T12:00:00Z')
datetime.datetime(1977, 6, 10, 12, 0, tzinfo=+0:00:00 UTC)

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

>>> aniso8601.parse_datetime('1977-06-10 12:00:00Z', delimiter=' ')
datetime.datetime(1977, 6, 10, 12, 0, tzinfo=+0:00:00 UTC)

UTC offsets are supported:

>>> aniso8601.parse_datetime('1979-06-05T08:00:00-08:00')
datetime.datetime(1979, 6, 5, 8, 0, tzinfo=-8:00:00 UTC)

If a UTC offset is not specified, the returned datetime will be naive:

>>> aniso8601.parse_datetime('1983-01-22T08:00:00')
datetime.datetime(1983, 1, 22, 8, 0)

Parsing dates

To parse a date represented in an ISO 8601 string:

>>> import aniso8601
>>> aniso8601.parse_date('1984-04-23')
datetime.date(1984, 4, 23)

Basic format is supported as well:

>>> aniso8601.parse_date('19840423')
datetime.date(1984, 4, 23)

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

>>> aniso8601.parse_date('1986-W38-1')
datetime.date(1986, 9, 15)

To parse an ISO 8601 ordinal date:

>>> aniso8601.parse_date('1988-132')
datetime.date(1988, 5, 11)

Parsing times

To parse a time formatted as an ISO 8601 string:

>>> import aniso8601
>>> aniso8601.parse_time('11:31:14')
datetime.time(11, 31, 14)

As with all of the above, basic format is supported:

>>> aniso8601.parse_time('113114')
datetime.time(11, 31, 14)

A UTC offset can be specified for times:

>>> aniso8601.parse_time('17:18:19-02:30')
datetime.time(17, 18, 19, tzinfo=-2:30:00 UTC)
>>> aniso8601.parse_time('171819Z')
datetime.time(17, 18, 19, tzinfo=+0:00:00 UTC)

Reduced accuracy is supported:

>>> aniso8601.parse_time('21:42')
datetime.time(21, 42)
>>> aniso8601.parse_time('22')
datetime.time(22, 0)

A decimal fraction is always allowed on the lowest order element of an ISO 8601 formatted time:

>>> aniso8601.parse_time('22:33.5')
datetime.time(22, 33, 30)
>>> aniso8601.parse_time('23.75')
datetime.time(23, 45)

Parsing durations

To parse a duration formatted as an ISO 8601 string:

>>> import aniso8601
>>> aniso8601.parse_duration('P1Y2M3DT4H54M6S')
datetime.timedelta(428, 17646)

Reduced accuracy is supported:

>>> aniso8601.parse_duration('P1Y')
datetime.timedelta(365)

A decimal fraction is allowed on the lowest order element:

>>> aniso8601.parse_duration('P1YT3.5M')
datetime.timedelta(365, 210)

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

>>> aniso8601.parse_duration('P1YT3,5M')
datetime.timedelta(365, 210)

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

>>> aniso8601.parse_duration('P0001-01-02T01:30:5')
datetime.timedelta(397, 5405)

The above treat years as 365 days and months as 30 days. If calendar level accuracy is required, the relative keyword argument can be used:

>>> import aniso8601
>>> from datetime import date
>>> one_month = aniso8601.parse_duration('P1M', relative=True)
>>> print one_month
relativedelta(months=+1)
>>> date(2003,1,27) + one_month
datetime.date(2003, 2, 27)
>>> date(2003,1,31) + one_month
datetime.date(2003, 2, 28)
>>> date(2003,1,31) + two_months
datetime.date(2003, 3, 31)

Since it a relative fractional month or year is not logical. A ValueError is raised when attempting to parse a duration with relative=True and fractional month or year:

>>> aniso8601.parse_duration('P2.1Y', relative=True)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/duration.py", line 29, in parse_duration
    return _parse_duration_prescribed(isodurationstr, relative)
  File "aniso8601/duration.py", line 119, in _parse_duration_prescribed
    raise ValueError('Fractional months and years are not defined for relative intervals.')
ValueError: Fractional months and years are not defined for relative intervals.

Parsing intervals

To parse an interval specified by a start and end:

>>> import aniso8601
>>> aniso8601.parse_interval('2007-03-01T13:00:00/2008-05-11T15:30:00')
(datetime.datetime(2007, 3, 1, 13, 0), datetime.datetime(2008, 5, 11, 15, 30))

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

>>> aniso8601.parse_interval('2007-03-01T13:00:00Z/P1Y2M10DT2H30M')
(datetime.datetime(2007, 3, 1, 13, 0, tzinfo=+0:00:00 UTC), datetime.datetime(2008, 5, 9, 15, 30, tzinfo=+0:00:00 UTC))

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

>>> aniso8601.parse_interval('P1M/1981-04-05')
(datetime.date(1981, 4, 5), datetime.date(1981, 3, 6))

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'))
[datetime.date(1981, 3, 6), datetime.date(1981, 4, 5)]

The end of an interval is given 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')
(datetime.date(2014, 11, 12), datetime.datetime(2014, 11, 12, 4, 54, 6, 500000))

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

>>> aniso8601.parse_repeating_interval('R3/1981-04-05/P1D')
<generator object date_generator at 0x7f698cdefc80>
>>> list(aniso8601.parse_repeating_interval('R3/1981-04-05/P1D'))
[datetime.date(1981, 4, 5), datetime.date(1981, 4, 6), datetime.date(1981, 4, 7)]

Repeating intervals are allowed to go in the reverse direction:

>>> list(aniso8601.parse_repeating_interval('R2/PT1H2M/1980-03-05T01:01:00'))
[datetime.datetime(1980, 3, 5, 1, 1), datetime.datetime(1980, 3, 4, 23, 59)]

Unbounded intervals are also allowed (Python 2):

>>> result = aniso8601.parse_repeating_interval('R/PT1H2M/1980-03-05T01:01:00')
>>> result.next()
datetime.datetime(1980, 3, 5, 1, 1)
>>> result.next()
datetime.datetime(1980, 3, 4, 23, 59)

or for Python 3:

>>> result = aniso8601.parse_repeating_interval('R/PT1H2M/1980-03-05T01:01:00')
>>> next(result)
datetime.datetime(1980, 3, 5, 1, 1)
>>> next(result)
datetime.datetime(1980, 3, 4, 23, 59)

Note that you should never try to convert a generator produced by an unbounded interval to a list:

>>> list(aniso8601.parse_repeating_interval('R/PT1H2M/1980-03-05T01:01:00'))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/__init__.py", line 140, in date_generator_unbounded
    currentdate += timedelta
OverflowError: date value out of range

The above treat years as 365 days and months as 30 days. If calendar level accuracy is required, the relative keyword argument can be used:

>>> aniso8601.parse_interval('2003-01-27/P1M', relative=True)
(datetime.date(2003, 1, 27), datetime.date(2003, 2, 27))
>>> aniso8601.parse_interval('2003-01-31/P1M', relative=True)
(datetime.date(2003, 1, 31), datetime.date(2003, 2, 28))
>>> aniso8601.parse_interval('P1Y/2001-02-28', relative=True)
(datetime.date(2001, 2, 28), datetime.date(2000, 2, 28)

Fractional years and months do not make sense for relative intervals. A ValueError is raised when attempting to parse an interval with relative=True and a fractional month or year:

>>> aniso8601.parse_interval('P1.1Y/2001-02-28', relative=True)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/interval.py", line 51, in parse_interval
    duration = parse_duration(firstpart, relative=relative)
  File "aniso8601/duration.py", line 29, in parse_duration
    return _parse_duration_prescribed(isodurationstr, relative)
  File "aniso8601/duration.py", line 119, in _parse_duration_prescribed
    raise ValueError('Fractional months and years are not defined for relative intervals.')
ValueError: Fractional months and years are not defined for relative intervals.

Date and time resolution

In some situations, it may be useful to figure out the resolution provided by an ISO 8601 date or time string. Two functions are provided for this purpose.

To get the resolution of a ISO 8601 time string:

>>> aniso8601.get_time_resolution('11:31:14') == aniso8601.resolution.TimeResolution.Seconds
True
>>> aniso8601.get_time_resolution('11:31') == aniso8601.resolution.TimeResolution.Minutes
True
>>> aniso8601.get_time_resolution('11') == aniso8601.resolution.TimeResolution.Hours
True

Similarly, for an ISO 8601 date string:

>>> aniso8601.get_date_resolution('1981-04-05') == aniso8601.resolution.DateResolution.Day
True
>>> aniso8601.get_date_resolution('1981-04') == aniso8601.resolution.DateResolution.Month
True
>>> aniso8601.get_date_resolution('1981') == aniso8601.resolution.DateResolution.Year
True

Tests

To run the unit tests, navigate to the source directory and run the tests for the python version being worked on (python2, python3):

$ python2 -m unittest discover aniso8601/tests/

or:

$ python3 -m unittest discover aniso8601/tests/

Contributing

aniso8601 is an open source project hosted on Bitbucket.

Any and all bugs are welcome on our issue tracker. Of particular interest are valid ISO 8601 strings that don’t parse, or invalid ones that do. At a minimum, bug reports should include an example of the misbehaving string, as well as the expected result. Of course patches containing unit tests (or fixed bugs) are welcome!

 
File Type Py Version Uploaded on Size
aniso8601-1.1.0.tar.gz (md5) Source 2015-10-21 48KB