[issue15443] datetime module has no support for nanoseconds
Vincenzo Ampolo vincenzo.amp...@gmail.com added the comment: Have a look to this python dev mailing list thread too: http://mail.python.org/pipermail/python-dev/2012-July/121123.html -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15443 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15443] datetime module has no support for nanoseconds
New submission from Vincenzo Ampolo vincenzo.amp...@gmail.com: As long as computers evolve time management becomes more precise and more granular. Unfortunately the standard datetime module is not able to deal with nanoseconds even if OSes are able to. For example if i do: print %.9f % time.time() 1343158163.471209049 I've actual timestamp from the epoch with nanosecond granularity. Thus support for nanoseconds in datetime would really be appreciated -- components: ctypes messages: 166326 nosy: Vincenzo.Ampolo priority: normal severity: normal status: open title: datetime module has no support for nanoseconds type: enhancement versions: Python 2.7 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15443 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15443] datetime module has no support for nanoseconds
Changes by Vincenzo Ampolo vincenzo.amp...@gmail.com: -- components: +Library (Lib) -ctypes ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15443 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15443] datetime module has no support for nanoseconds
Vincenzo Ampolo vincenzo.amp...@gmail.com added the comment: On 07/24/2012 01:28 PM, Marc-Andre Lemburg wrote: I would be interested in an actual use case for this. Alice has a dataset with nanosecond granularity. He wants to make a python library to let Bob access the dataset. Nowadays Alice has to implement her own time class losing all the flexibility of the datetime module. With this enhancement she can provide a library that just uses the standard python datetime module. Her library will get the needed time format, including nanoseconds. Many python sql libraries, like the one in django e the one in web2py, relay on datetime objects for time representation. Bob has a web2py website that has some data with nanosecond granularity. Nowadays Bob has to store this data as a string or a long number without the ability to use the powerful datetime module. With this enhancement Bob doesn't need to build or learn another interface, he can just use the datetime module using microseconds or nanoseconds as needed. Google search for python datetime nanoseconds shows more than 141k results: https://www.google.com/search?sourceid=chromeie=UTF-8q=python+time#hl=enbiw=1615bih=938sclient=psy-abq=python+datetime+nanosecondsoq=python+datetime+nanoseconds So this is definitively a requested feature. And as soon as technology evolves more people will ask for it. I imagine something like: import datetime nano_time = datetime.datetime(year=2012, month=07, day=24, hour=14, minute=35, second=3, microsecond=53, nanosecond=27) in case you need nanosecond granularity. if you don't need it just skip the nanosecond part and the module works like it's now. Of course strftime format should be updated to support nanoseconds. I can write a patch if some dev can maybe review it. Before someone takes the datetime source code and starts a third part module that supports nanoseconds, I think this enhancement has almost null impact in existing code and makes the datetime module even more powerful. It's up to the Cpython admins to decide between maintaining datetime module up to date with new needs or let third part modules take care of those lacks. Best Regards, -- Vincenzo Ampolo http://vincenzo-ampolo.net http://goshawknest.wordpress.com -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15443 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15443] datetime module has no support for nanoseconds
Vincenzo Ampolo vincenzo.amp...@gmail.com added the comment: This is a real use case I'm working with that needs nanosecond precision and lead me in submitting this request: most OSes let users capture network packets (using tools like tcpdump or wireshark) and store them using file formats like pcap or pcap-ng. These formats include a timestamp for each of the captured packets, and this timestamp usually has nanosecond precision. The reason is that on gigabit and 10 gigabit networks the frame rate is so high that microsecond precision is not enough to tell two frames apart. pcap (and now pcap-ng) are extremely popular file formats, with millions of files stored around the world. Support for nanoseconds in datetime would make it possible to properly parse these files inside python to compute precise statistics, for example network delays or round trip times. Other case is in stock markets. In that field information is timed in nanoseconds and have the ability to easily deal with this kind of representation natively with datetime can make the standard module even more powerful. The company I work for is in the data networking field, and we use python extensively. Currently we rely on custom code to process timestamps, a nanosecond datetime would let us avoit that and use standard python datetime module. Best Regards, --- Vincenzo Ampolo http://vincenzo-ampolo.net http://goshawknest.wordpress.com -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15443 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15443] datetime module has no support for nanoseconds
Changes by Vincenzo Ampolo vincenzo.amp...@gmail.com: -- versions: +Python 2.7 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15443 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15443] datetime module has no support for nanoseconds
Vincenzo Ampolo vincenzo.amp...@gmail.com added the comment:
On 07/24/2012 04:20 PM, R. David Murray wrote:
R. David Murray rdmur...@bitdance.com added the comment:
Are the nanosecond timestamps timestamps or strings? If they are timestamps
it's not immediately obvious why you want to convert them to datetime
objects, so motivating that would probably help. On the other hand the fact
that you have an application that does so is certain an argument for real
world applicability.
It depends. When they are exported for example as csv (this can be the
case of market stock) or json (which is close to my case) that's a
string so having a datetime object may be very helpful in doing datetime
adds, subs, , deltas and in changing representation to human readable
format thanks to strftime() without loosing precison and maintaining
readability.
Think about a web application. User selects year, month, day, hour,
minute, millisecond, nanosecond of an event and the javascript does a
ajax call with time of this format (variant of iso8601):
-MM-DDTHH:MM:SS.mmnnn (where nnn is the nanosecond representation).
The python server takes that string, converts to a datetime, does all
the math with its data and gives the output back using labeling data
with int(nano_datetime.strftime('MMSSmmnnn')) so I've a sequence
number that javascript can sort and handle easily.
It's basically the same you already do nowadays at microseconds level,
but this time you have to deal with nanosecond data.
I agree with the YAGNI principle and I think that we have a clear
evidence of a real use case here indeed.
Best Regards
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