business.py

Date calculations based on business calendars.

This is basically a python version of a ruby gem.

Documentation

To get business, simply:

$ python setup.py install

Getting started

Get started with business by creating an instance of the calendar class, passing in a hash that specifies with days of the week are considered working days, and which days are holidays.

calendar = business.Calendar(
  working_days=['mon', 'tue', 'wed', 'thu', 'fri'],
  holidays=["01/01/2014", "03/01/2014"]
)

A few calendar configs are bundled with the gem (see lib/business/data for details). Load them by calling the load class method on Calendar.

calendar = business.Calendar.load("weekdays")

Checking for business days

To check whether a given date is a business day (falls on one of the specified working days, and is not a holiday), use the is_business_day method on Calendar.

>>> calendar.is_business_day("Monday, 9 June 2014")
True
>>> calendar.is_business_day("Sunday, 8 June 2014")
False

Custom calendars

To use a calendar you've written yourself, you need to add the directory it's stored in as an additional calendar load parameter:

calendar = business.Calendar.load("your_calendar",
                                  data_path="path/to/your/calendar/directory")

Business day arithmetic

The add_business_days and subtract_business_days are used to perform business day arithemtic on dates.

>>> date = datetime.strptime("Thursday, 12 June 2014", "%A, %d %B %Y")
>>> calendar.add_business_days(date, 4).strftime("%A, %d %B %Y")
'Wednesday, 18 June 2014'
>>> calendar.subtract_business_days(date, 4).strftime("%A, %d %B %Y")
'Friday, 06 June 2014'

The roll_forward and roll_backward methods snap a date to a nearby business day. If provided with a business day, they will return that date. Otherwise, they will advance (forward for roll_forward and backward for roll_backward) until a business day is found.

>>> date = datetime.strptime("Saturday, 14 June 2014", "%A, %d %B %Y")
>>> calendar.roll_forward(date).strftime("%A, %d %B %Y")
'Monday, 16 June 2014'
>>> calendar.roll_backward(date).strftime("%A, %d %B %Y")
'Friday, 13 June 2014'

To count the number of business days between two dates, pass the dates to business_days_between. This method counts from start of the first date to start of the second date. So, assuming no holidays, there would be two business days between a Monday and a Wednesday.

>>> date = datetime.strptime("Saturday, 14 June 2014", "%A, %d %B %Y")
>>> calendar.business_days_between(date, date + timedelta(days=7))
5

But there's already a library that does this

In ruby, sure. I'm doing this for python because I'm a monster. Also some people use Django I suppose.