pytz and Etc/GMT-5
python, pytz, timezone, utc
Solution
This is apparently a POSIX thing. From Wikipedia:
In order to conform with the POSIX style, those zones beginning with "Etc/GMT" have their sign reversed from what most people expect. In this style, zones west of GMT have a positive sign and those east have a negative sign.
Problem
I'm having trouble understanding the conversion between the "Etc/GMT-5" timezone and UTC in pytz. ``` >>> dt = datetime(2009, 9, 9, 10, 0) # September 9 2009, 10:00 >>> gmt_5 = pytz.timezone("Etc/GMT-5") >>> gmt_5.localize(dt) datetime.datetime(2009, 9, 9, 10, 0, tzinfo=<StaticTzInfo 'Etc/GMT-5'>) ``` Everything is fine so far, but then I try to convert that to UTC: ``` >>> gmt_5.localize(dt).astimezone(pytz.utc) datetime.datetime(2009, 9, 9, 5, 0, tzinfo=<UTC>) ``` So to me it seems that when converting from 10:00 in GMT-5 to UTC I get 05:00? I would expect pytz to give me 15:00 instead. What am I missing? EDIT: I have confirmed that timezone conversion for the US/Eastern timezone works just as I'd expect: ``` >>> eastern = pytz.timezone("US/Eastern") >>> eastern.localize(dt) datetime.datetime(2009, 9, 9, 10, 0, tzinfo=...) # Too long >>> pytz.utc.normalize(eastern.localize(dt).astimezone(pytz.utc)) datetime.datetime(2009, 9, 9, 14, 0, tzinfo=<UTC>) ``` EDIT 2: I have confirmed that when I use Etc/GMT+5 I get 15:00, which is what I'd expect to get from Etc/GMT-5. Is this a pytz bug?