[Python-bugs-list] [ python-Bugs-656817 ] Bug in week calculation of time module

[noreply@sourceforge.net]

Bugs item #656817, was opened at 2002-12-20 14:37
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=656817&group_id=5470

Category: Python Library
Group: Python 2.2.1
Status: Open
Resolution: None
Priority: 5
Submitted By: Christian Loth (chloth)
Assigned to: Nobody/Anonymous (nobody)
Summary: Bug in week calculation of time module

Initial Comment:
Noticed while writing an application in connection with
PostgreSQL.
Because of Leapyears, the year 1998 had 53 weeks,
instead of
the normal 52 weeks. PostgreSQL does ist correctly:
SELECT EXTRACT(WEEK FROM TIMESTAMP'1998-31-12 20:38:40');
 date_part
-----------
        53
(1 row)

However the python equivalent fails, neither U nor W gets
it right:
>>> int(strftime("%U", strptime("1998-12-31", "%Y-%m-%d")))
52
>>> int(strftime("%W", strptime("1998-12-31", "%Y-%m-%d")))
52
>>>



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>Comment By: Christian Loth (chloth)
Date: 2002-12-21 10:45

Message:
Logged In: YES 
user_id=553797

If that is so, how do you explain the following (again
PostgreSQL vs.
Python comparison).

SELECT EXTRACT(WEEK FROM TIMESTAMP'1999-12-31 20:38:40');
 date_part
-----------
        52
(1 row)

>>> int(strftime("%U", strptime("1999-12-31", "%Y-%m-%d")))
52

Does that mean, according to your explaination, that 1999
had 53 weeks? (which of course it hadn't).


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Comment By: Tim Peters (tim_one)
Date: 2002-12-20 18:13

Message:
Logged In: YES 
user_id=31435

Have you read the docs for strftime()?  strftime() is defined by 
the ANSI C standard, not by SQL  1998-01-01 was in "week 
0" according to ANSI C, so the 53rd week of the year is week 
52.

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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=656817&group_id=5470