How to parse string dates with 2-digit year?

Question

I need to parse strings representing 6-digit dates in the format yymmdd where yy ranges from 59 to 05 (1959 to 2005). According to the time module docs, Python's default pivot year is 1969 which won't work for me.

Is there an easy way to override the pivot year, or can you suggest some other solution? I am using Python 2.7. Thanks!

Dehorn

Answer 1

I'd use datetime and parse it out normally. Then I'd use datetime.datetime.replace on the object if it is past your ceiling date -- Adjusting it back 100 yrs.:

import datetime
dd = datetime.datetime.strptime(date,'%y%m%d')
if dd.year > 2005:
   dd = dd.replace(year=dd.year-100)

Emie

Note that 000229 would raise an error because 2100/02/29 does not exist, even though 2000/02/29 exists. – Unblushing

Answer 2

Prepend the century to your date using your own pivot:

  year = int(date[0:2])
  if 59 <= year <= 99:
      date = '19' + date
  else
      date = '20' + date

and then use strptime with the %Y directive instead of %y.

Osset

There is a missing ':' after the else statement when using Py3. – Intercommunion

Answer 3

import datetime
date = '20-Apr-53'
dt = datetime.datetime.strptime( date, '%d-%b-%y' )
if dt.year > 2000:
    dt = dt.replace( year=dt.year-100 )
                     ^2053   ^1953
print dt.strftime( '%Y-%m-%d' )

Prepare

Answer 4

You can also perform the following:

today=datetime.datetime.today().strftime("%m/%d/%Y")
today=today[:-4]+today[-2:]

Enoch

Answer 5

Recently had a similar case, ended up with this basic calculation and logic:

pivotyear = 1969
century = int(str(pivotyear)[:2]) * 100

def year_2to4_digit(year):
    return century + year if century + year > pivotyear else (century + 100) + year

Tersanctus

Answer 6

If you are dealing with very recent dates as well as very old dates and want to use the current date as a pivot (not just the current year), try this code:

import datetime
def parse_date(date_str):
    parsed = datetime.datetime.strptime(date_str,'%y%m%d')
    current_date = datetime.datetime.now()
    if parsed > current_date:
        parsed = parsed.replace(year=parsed.year - 100)
    return parsed

Osy