Doing date/time + TZ math in python

[Joshua J. Kugler]

I've read docs (datetime, time, pytz, mx.DateTime), googled, and
experimented. I still don't know how to accomplish what I want to
accomplish.

I'm loading up a bunch of date/time data that I then need to do math on to
compare it to the current date/time. I can get the current time easily
enough:

currentTime = datetime.datetime.now(pytz.timezone('America/Anchorage'))

Then, I want to import data/time pairs that are in "%Y-%m-%d %H:%M:%S"
format.

So, I do:

For each loop, extract time data, blah, blah, then:
readingTime = datetime.datetime(rYr, rMo, rDay, rHr, rMin, rSec,
tzinfo=pytz.timezone('America/Anchorage'))

The problem is, how do I create a datetime object and tell it that it's
America/Anchorage *daylight savings time* instead of whatever the system is
currently set at? pytz only has America/Anchorage, and I saw no way to
tell it explicitly that the timezone is in Daylight instead of Standard
time (e.g. using AKST vs. AKDT for the time zone).

I'm sure there is a way to do it, and I'm sure it's quite simple, but it
hasn't jumped out at me yet. Is there a module that I haven't seen that
would be better suited for this?

Thanks!

j

 

[wittempj]

I've read docs (datetime, time, pytz, mx.DateTime), googled, and
experimented. I still don't know how to accomplish what I want to
accomplish.

I'm loading up a bunch of date/time data that I then need to do math on to
compare it to the current date/time. I can get the current time easily
enough:

currentTime = datetime.datetime.now(pytz.timezone('America/Anchorage'))

Then, I want to import data/time pairs that are in "%Y-%m-%d %H:%M:%S"
format.

So, I do:

For each loop, extract time data, blah, blah, then:
readingTime = datetime.datetime(rYr, rMo, rDay, rHr, rMin, rSec,
tzinfo=pytz.timezone('America/Anchorage'))

The problem is, how do I create a datetime object and tell it that it's
America/Anchorage *daylight savings time* instead of whatever the system is
currently set at? pytz only has America/Anchorage, and I saw no way to
tell it explicitly that the timezone is in Daylight instead of Standard
time (e.g. using AKST vs. AKDT for the time zone).

I'm sure there is a way to do it, and I'm sure it's quite simple, but it
hasn't jumped out at me yet. Is there a module that I haven't seen that
would be better suited for this?

Thanks!

j

--
Joshua Kugler
Lead System Admin -- Senior Programmer
http://www.eeinternet.com
PGP Key: http://pgp.mit.edu/ ID 0xDB26D7CE

It looks like3 you're 9 hours in this example:
http://docs.python.org/lib/datetime-tzinfo.html, see e.g.
http://www.worldtimezone.com/index12.php

 

[Joshua J. Kugler]

It looks like3 you're 9 hours in this example:
http://docs.python.org/lib/datetime-tzinfo.html, see e.g.
http://www.worldtimezone.com/index12.php

Right, I know I'm at GMT-9, and tzinfo correctly deduces that when it
creates an object. But what if I were currently at GMT-8 (my time zone on
daylight savings time) and I was importing data created during standard
time? How would I create an object and tell it this is America/Anchorage
on standard time, or conversely, how would I right now create and object
and tell it to use daylight time? In other words, how can I explicitly
specify whether or not the time object being created is daylight savings
time or not? I did not see that option in the documentation reading I did.

Thanks!

j