mktime adding an hour in April (naive struct)?

[barnburnr]

BPO	10102
Nosy	@abalkin
Files	mktimeissue.py: Test script

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2010-10-14.15:37:31.380>
created_at = <Date 2010-10-14.14:08:02.865>
labels = ['type-bug', 'invalid']
title = 'mktime adding an hour in April (naive struct)?'
updated_at = <Date 2010-10-14.16:54:05.536>
user = 'https://bugs.python.org/barnburnr'

bugs.python.org fields:

activity = <Date 2010-10-14.16:54:05.536>
actor = 'barnburnr'
assignee = 'none'
closed = True
closed_date = <Date 2010-10-14.15:37:31.380>
closer = 'belopolsky'
components = []
creation = <Date 2010-10-14.14:08:02.865>
creator = 'barnburnr'
dependencies = []
files = ['19232']
hgrepos = []
issue_num = 10102
keywords = []
message_count = 3.0
messages = ['118662', '118673', '118690']
nosy_count = 2.0
nosy_names = ['belopolsky', 'barnburnr']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = None
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue10102'
versions = []

[barnburnr]

Just starting to dabble in the world of time and datetime objects. I was converting an array of datetime objects to an array of floats via mktime to do some data analysis. I have ran into an issue where mktime seems to be adding an hour on April 6, 2003. Attached is an example script which I used to create the below output:

Python version: (2, 6, 5, 'final', 0)
Epoch: time.struct_time(tm_year=1970, tm_mon=1, tm_mday=1, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=3, tm_yday=1, tm_isdst=0)
First datetime: 2003-04-06 02:58:17
Second datetime: 2003-04-06 03:13:17
Is first datetime prior to second?: True
First datetime, time struct: time.struct_time(tm_year=2003, tm_mon=4, tm_mday=6, tm_hour=2, tm_min=58, tm_sec=17, tm_wday=6, tm_yday=96, tm_isdst=-1)
Second datetime, time struct: time.struct_time(tm_year=2003, tm_mon=4, tm_mday=6, tm_hour=3, tm_min=13, tm_sec=17, tm_wday=6, tm_yday=96, tm_isdst=-1)
Is first time struct prior to second?: True
First timestamp generated by mktime: 1049623097.0
Second timestamp generated by mktime: 1049620397.0
Is first timestamp less than second timestamp?: False
First recovered datetime: 2003-04-06 03:58:17
Second recovered datetime: 2003-04-06 03:13:17
Is first recovered prior to second recovered?: False
Is first recovered datetime same as original?: False
Is second recovered datetime same as original?: True

[abalkin]

It looks like you have just discovered the joys of daylight saving time. The problem with your example is that datetime(2003,4,6,2,58,17) is not a valid time in your timezone (most likely you are in the US). In the US, prior to 2007, the clocks moved 1 hour ahead at 2AM on the first Sunday in April. An thus 1:59 AM was followed by 3:00 AM and 2:58:17 never occurred.

See the following link for detailed discussion of these issues:

http://docs.python.org/dev/py3k/library/datetime.html#tzinfo-objects

[barnburnr]

Wow. Should have caught that. Thanks for the response.

Kevin