Hello Anthony,
Thanks for your reply. I did a little bit more searching and found the
discussion datetime objects on tables (
http://comments.gmane.org/gmane.comp.python.pytables.user/2469) ,which is a
bit more recent. In it you list your order of preference for storing
timestamps:
1. Create a numpy dtype or PyTables description that matches the structure
of datetime to your desired precision and save them in a Table. If you want
to save timezone information as well, I might add an extra length-3 string
column and save the str representation of the tzinfo field ('UTC', 'KST',
'EDT').
[Could you give an example?]
The best I could come up with so far is to create a column of type
tables.Time32Col() and then transform my datetime object into a timestamp
and store it. For example,
In [1]: import tables, pytz
In [2]: from datetime import datetime, timedelta
In [3]: from time import mktime
In [4]: import calendar
In [5]: dt = datetime.utcnow().replace(tzinfo=pytz.UTC)
In [6]: dt
Out[6]: datetime.datetime(2012, 6, 19, 15, 22, 19, 892159, tzinfo=<UTC>)
In [7]: ts = calendar.timegm(dt.timetuple())
In [8]: ts
Out[8]: 1340119339
I can then store ts in my table, and retrieve it with
In [35]: datetime.utcfromtimestamp(tbl.cols.timestamp[0])
Out[35]: datetime.datetime(2012, 6, 19, 15, 22, 19)
although, at this point I've lost the timezone.
Anyway, I am a little bit confused, because I don't understand the
difference between a Time32Col() and a Int32Col() in the example that I've
written. Do you have a better example?
Thanks!
On Tue, Jun 19, 2012 at 2:16 AM, Anthony Scopatz <scop...@gmail.com> wrote:
> Hey Aquil,
>
> Yes, the string method certainly works. The other thing you could do that
> isn't mentioned in that post is have a table or 2D array whose first
> column is the float timestamp [1] and whose second column is a string repr
> of just the timezone name (or a int or float of the offset in sec of the
> timezone). This will likely be faster.
>
> All of the strategies mentioned will work, but will have varying speeds.
> I personally prefer anything with a timestamp since it relies on the
> canonical form.
>
> Be Well
> Anthony
>
> PS I am sorry that you have to deal with timezones. They are a real pain!
>
> 1. http://pytables.github.com/usersguide/libref.html#tables.Time64Col
>
> On Mon, Jun 18, 2012 at 10:05 PM, Aquil H. Abdullah <
> aquil.abdul...@gmail.com> wrote:
>
>> I need to store dates and timezone aware datetimes in a PyTable.
>> Currently, I am storing values of those types as ISO 8601 strings. I ran
>> across the thread pytables for timeseries data (
>> http://osdir.com/ml/python.pytables.user/2007-11/msg00036.html) which
>> leads me to believe that what I am doing is the best way to store these
>> types of values, but I just wanted to check in case I am missing something.
>>
>> Regards,
>>
>> --
>> Aquil H. Abdullah
>> aquil.abdul...@gmail.com
>>
>>
>> ------------------------------------------------------------------------------
>> Live Security Virtual Conference
>> Exclusive live event will cover all the ways today's security and
>> threat landscape has changed and how IT managers can respond. Discussions
>> will include endpoint security, mobile security and the latest in malware
>> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>> _______________________________________________
>> Pytables-users mailing list
>> Pytables-users@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/pytables-users
>>
>>
>
>
> ------------------------------------------------------------------------------
> Live Security Virtual Conference
> Exclusive live event will cover all the ways today's security and
> threat landscape has changed and how IT managers can respond. Discussions
> will include endpoint security, mobile security and the latest in malware
> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
> _______________________________________________
> Pytables-users mailing list
> Pytables-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/pytables-users
>
>
--
Aquil H. Abdullah
aquil.abdul...@gmail.com
------------------------------------------------------------------------------
Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and
threat landscape has changed and how IT managers can respond. Discussions
will include endpoint security, mobile security and the latest in malware
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
_______________________________________________
Pytables-users mailing list
Pytables-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/pytables-users
