[Numpy-discussion] datetime update

Travis Oliphant teoliphant at gmail.com
Tue Nov 24 18:24:25 EST 2009

On Nov 23, 2009, at 6:53 PM, Pierre GM wrote:

> On Nov 23, 2009, at 6:42 PM, Travis Oliphant wrote:
>> I've made a few changes to datetime today and spent some time  
>> looking over what is there and what remains to be implemented.
> As always, many thanks for your work !!
>> Basically, the biggest thing left to do is to implement the low- 
>> level casting functions to and from datetime types and other numpy  
>> types.
>> In addition, the ufuncs need some auditing to make sure the right  
>> thing is being done when mixing different units.  After that, lots  
>> and lots of additional tests need to be written.      Once that is  
>> done, then most of the features should be available, but I suspect  
>> a few lingering issues might crop up and require fixing or fleshing  
>> out as well.
>> I was hoping that someone would be able to contribute more tests  
>> for datetime.    I will spend some time on the casting functions  
>> over the next few weeks and write a few tests.
> Fortunately, the new modifications will make it easier to write such  
> tests... But in any case, we can assume that what is proposed in the  
> NEP should work, right ?

Yes, that is correct.
>> I also removed numpy.datetime and numpy.timedelta from the  
>> namespace (replaced them with numpy.datetime_ and  
>> numpy.timedelta_).   These were just short-hand for  
>> numpy.datetime64 and numpy.timedelta64 respectively.   Avoiding the  
>> collision seemed like a good idea.
>> Right now, what works is "viewing" arrays as datetime data-types  
>> and getting and setting date-time arrays using datetime objects.    
>> I would like to improve it so that setting with strings, integers,  
>> and other Python objects works as well.
> Did you use any of Marty Fuhry's GSoC work ? What are the potential  
> issues that could prevent an easy integration ?

Yes, I did actually.   His work was quite helpful in converting from  
date-time objects.   The major issues were the approach taken to a few  
of the functions was not quite right, but quite a bit of the raw code  
I just used.    Marty deserves kudos for his work here.   It was very  
useful and helpful.   Please pass that on to him.

>> Also, adding simple integers works, but
>> Dave C suggested removing the new C-API calls which sounds like a  
>> good idea to me for 1.4.0.   Which functions get exported into the  
>> C-API for 1.5.0 could then receive some discussion.
> Wouldn't it be easier to leave the C-APi as it is now, even for  
> 1.4.0, but not to advertize it before 1.5.0 ?

Not necessarily.   My understanding is that we just have to turn-off  
exposure of the API and leave everything else the same.


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