parse_date.py

import datetime

def parse_date(date_string, format='%Y-%m-%d', seg=','):
  ''' defualt date_string == 'yesterday'
  available alias 'week','month','year' or timestr: '2013-0101'
  relativedate = latest_parse_date or today

  parse_date('2011-01-01')
  => datetime(2011,01,01)

  parse_date('2011-01-02,') 
  parse_date('2011-01-02,yesterday')
  => [datetime(2011,01,01), parse_date('2010-12-01')]
  '''
  today = datetime.datetime.today()
  def _parse(date_string, start=today):
    try:
      end = datetime.datetime.strptime(date_string, format)
    except:
      if date_string == 'month':
        if start.month == 1:
          end = start.replace(year=start.year-1, month=12)
        else:
          end = start.replace(month=start.month-1)
      else:
        yesterday =  start - datetime.timedelta(days=1)
        end = {
          'yesterday': yesterday,
          'week': start - datetime.timedelta(days=6),
          'year': start.replace(year=start.year-1),
        }.get(date_string, yesterday)
    return end

  if seg in date_string:
    ds = date_string.split(seg)
    ret = []
    for s in ds:
      last_d = ret[-1] if ret else today
      d = _parse(s.strip(), last_d)
      ret.append(d)
    return ret
  else:
    return _parse(date_string)

支持参数(def_arg='yesterday')

2013-09-13

2013-09-13, 2013-09-23

yesterday

week

month

year