yyyymmdd

Convenient Date and DateRange classes.

Date

A yyyymmdd-formatted date.

Date is a subclass of datetime.date, and is mostly (but not fully) compatible with it.

It supports flexible creation of Date objects, e.g.: from a yyyymmdd string, from delta (number of days relative to today), aliases ('yesterday', 'today', 'MIN', 'MAX', etc.), from a datetime.date object, etc.

It defines convenient date arithmetic: Date +/- int => Date, Date - Date => int.

Here is an example:

>>> from yyyymmdd import Date
>>> import datetime
>>>
>>> Date.today()
Date(20200522)
>>> Date('-7')  # a week ago
Date(20200515)
>>> Date(20191123) == Date('20191123') == Date('2019-11-23') == Date(datetime.date(2019, 11, 23))
True
>>> Date(20191123).replace(month=1, day=1)
Date(20190101)
>>> Date('19991231') + 1
Date(20000101)
>>> Date('tomorrow') - Date('yesterday')
2
>>> Date('tomorrow') - 1 == Date('today')
True
>>> x = Date(20191123)
>>> x.yyyy + x.mm + x.dd
'20191123'

DateRange

A DateRange is a range -like type, whose elements are Date objects.

This class mostly follows the semantics of the builtin range type. E.g., stop is exclusive, behavior of steps, negative steps, slicing, range1 == range2 iff tuple(range1) == tuple(range2), etc.

Creation of DateRange objects is flexible. start and stop parameters are converted to Date automatically. See Date class for values which can be converted.

Here is an example:

from yyyymmdd import Date, DateRange

>>> from yyyymmdd import Date, DateRange
>>>
>>> len(DateRange('today', 'today'))  # empty
0
>>> DateRange.from_string('yesterday:yesterday') == DateRange.empty()
True
>>> len(DateRange.from_string('-7:-1'))  # start and stop are relative to today
6
>>> DateRange.from_string('2020501')  # a singleton range
DateRange(2020501, 2020502)
>>> x = DateRange.from_string('2020401:2020515:7')  # 1-week step
>>> list(x)
[Date(2020401), Date(2020408), Date(2020415), Date(2020422), Date(2020429), Date(2020506), Date(2020513)]
>>> x[0], x[-1]
(Date(2020401), Date(2020513))
>>> x[1:3]
DateRange(2020408, 2020422, 7)
>>> Date(2020422) in x
True
>>> list(DateRange.from_string('2020515:2020401:-7'))  # negative step
[Date(2020515), Date(2020508), Date(2020501), Date(2020424), Date(2020417), Date(2020410), Date(2020403)]
>>> DateRange.from_string('20200101:%+31')  # "%" means "the date on the other side"
DateRange(20200101, 20200201)
>>> DateRange.from_string('%-365:20200101')  # "%" means "the date on the other side"
DateRange(20190101, 20200101)

ArgumentParser integration, powered by apegears

The Date and DateRange types can be used as cli argument types, when using apegears' ArgumentParser.

Here is an example:

>>> from yyyymmdd import Date, DateRange
>>> from apegears import ArgumentParser
>>>
>>> parser = ArgumentParser()
>>> parser.add_optional('x', type=Date)
>>> parser.add_optional('dates', 'd', type=DateRange)

>>> print(parser.parse_args('-x 20191123 --dates yest:tomorrow'.split()))
Namespace(dates=DateRange(20200521, 20200523), x=Date(20191123))  # if today is 20200522

>>> print(parser.parse_args('-h'.split()))
usage: [-h] [-x DATE] [--dates DATE_RANGE]

optional arguments:
  -h, --help            show this help message and exit
  -x DATE               Date, like: yyyymmdd, +days, -days, "yesterday", etc.
  --dates DATE_RANGE, -d DATE_RANGE
                        DateRange, like: "DATE:DATE" or "DATE:DATE:STEP"

If you prefer using the standard argparse.ArgumentParser, you can define Date arguments using type=Date, and DateRange arguments using type=DateRange.from_string. This isn't as powerful as using apegears (no default argument names, no default help message, no default metavar, etc.).

Installation

Using pip:

pip install yyyymmdd