Convert a date string into YYYYMMDD

I've got a bunch of date strings in this form: -

30th November 2009
31st March 2010
30th September 2010

I want them like this: -

YYYYMMDD

Currently I'm doing this: -

  parsed_date = "30th November 2009"
  part = parsed_date.split(' ')
  daymonth = part[0].strip(string.ascii_letters)
  mytime = daym开发者_StackOverflow社区onth+" "+part[1]+" "+part[2]
  time_format = "%d %B %Y"
  cdate = time.strptime(mytime, time_format)
  newdate = str(cdate[0])+str(cdate[1])+str(cdate[2])

It works, but I'm sure there is a better way...

Try dateutil:

from dateutil import parser

dates = ['30th November 2009', '31st March 2010', '30th September 2010']

for date in dates:
    print parser.parse(date).strftime('%Y%m%d')

output:

20091130
20100331
20100930

or if you want to do it using standard datetime module:

from datetime import datetime

dates = ['30th November 2009', '31st March 2010', '30th September 2010']

for date in dates:
    part = date.split()
    print datetime.strptime('%s %s %s' % (part[0][:-2]), part[1], part[2]), '%d %B %Y').strftime('%Y%m%d')

You can almost do this with a combination of strptime and strptime from the datetime module.

The problem we have is that the built-in formats support dates like 30 November 2010 but not 30th November 2010. So in the example below I've used a regular expression substitution to strip out the problem characters. (The regular expression uses a look-behind to see if "st", "nd", "rd" or "th" is preceeded by a digit, and if so replaces it with the empty string, thus removing it from the string.)

>>> import re
>>> from datetime import datetime
>>> mydate = "30th November 2009"
>>> mydate = re.sub("(?<=\d)(st|nd|rd|th)","",mydate)
>>> mydate
'30 November 2009'
>>> mydatetime = datetime.strptime(mydate,"%d %B %Y")
>>> mydatetime
datetime.datetime(2009, 11, 30, 0, 0)
>>> mydatetime.strftime("%Y%M%d")
'20090030'

In python 3.7, you can use isoformat()

>>> from datetime import datetime
>>> datetime.today().date().isoformat().replace("-", "")
'20190220'