weeks/months range

all_months_like_ever.py

from datetime import timedelta, datetime
from dateutil.relativedelta import relativedelta


def get_months_range(base_date=None, months_back=0):
    """
    Returns calendar month for given date

    Args:
        base_date: date to be used, date.today is default
        months_back: how many months to looks back
    Returns:
        tuple: (start, end)
    """

    months_ago = months_back % 12
    years_ago = months_back / 12

    if base_date is None:
        base_date = datetime.today()

    date_adjusted = datetime(
        year=base_date.year,
        month=base_date.month,
        day=1,
        hour=0,
        minute=0)

    start_date = date_adjusted - relativedelta(months=months_ago, years=years_ago)
    end_date = start_date + relativedelta(months=1, days=-1,
                                          hours=23, minutes=59)

    assert (end_date - start_date).days in (27, 28, 29, 30, 31)
    return start_date, end_date

for i in range(10):
    print i, get_months_range(months_back=i)

all_weeks_like_ever.py

from datetime import timedelta, datetime

def get_week_range(base_date=None, weeks_back=0):
      """
      Returns calendar week for given date

      Args:
          base_date: date to be used, date.today is default
          weeks_back: how many weeks to looks back
      Returns:
          tuple: (start, end)
      """

      if base_date is None:
          base_date = datetime.today()

      date_adjusted = datetime(
          year=base_date.year,
          month=base_date.month,
          day=base_date.day,
          hour=0,
          minute=0)

      start_date = date_adjusted - timedelta(days=base_date.isoweekday() - 1,
                                             weeks=weeks_back)
      end_date = start_date + timedelta(days=6, hours=23, minutes=59)

      assert start_date.isoweekday() == 1
      assert end_date.isoweekday() == 7
      return start_date, end_date

for i in range(105132): print i, get_week_range(weeks_back=i)