Python Strptime formatting

Question

I'm running into an issue with Date time in python. Here's my stack trace:

28/09/12
Traceback (most recent call last):
  File "product-release-by-year.py", line 49, in <module>
    get_earliest_order_date(fin)
  File "product-release-by-year.py", line 25, in get_earliest_order_date
    date = datetime.datetime.strptime(order_date, '%d/%m/%Y').date()
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_strptime.py", line 325, in _strptime
    (data_string, format))
ValueError: time data '28/09/12' does not match format '%d/%m/%Y'

And the relevant bit of code:

def get_earliest_order_date(fin):
    # CSV Headers
    product_col = 1
    order_col = 0

    f = open(fin, 'rb')
    try:
        reader = csv.reader(f, delimiter=";")
        next(reader, None) 
        for row in reader:

            product_name = row[product_col]

            order_date = row[order_col]
            print order_date

            date = datetime.datetime.strptime(order_date, '%d/%m/%Y').date()

            if product_name not in products:
                products[product_name] = date
            else:
                if date < products[product_name]:
                    products[product_name] = date
    finally:
        f.close()

As far as I can see, the format string should be correct? This same call to strptime works when inputting the string directly via the terminal.

Any ideas?

Martijn Pieters · Accepted Answer · 2014-05-09 16:16:34Z

4

%Y expects a year with four digits, including the century. Use %y to parse dates with a 2-digit year.

Demo:

>>> import datetime
>>> order_date = '28/09/12'
>>> datetime.datetime.strptime(order_date, '%d/%m/%Y')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/mj/Development/Library/buildout.python/parts/opt/lib/python2.7/_strptime.py", line 325, in _strptime
    (data_string, format))
ValueError: time data '28/09/12' does not match format '%d/%m/%Y'
>>> datetime.datetime.strptime(order_date, '%d/%m/%y')
datetime.datetime(2012, 9, 28, 0, 0)

%y adds a century following the POSIX convention for C strptime:

%y
The year within century (0-99). When a century is not otherwise specified, values in the range 69-99 refer to years in the twentieth century (1969-1999); values in the range 00-68 refer to years in the twenty-first century (2000-2068).

edited May 9, 2014 at 16:16

answered May 9, 2014 at 16:08

Martijn Pieters

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