[yt-users] Total Active Particles?

[Nathan Goldbaum]

Well, Dave nerd-sniped me:

https://bitbucket.org/yt_analysis/yt/pull-requests/2176

Hopefully this will be in yt 3.3.

On Fri, May 13, 2016 at 5:05 PM, Nathan Goldbaum <nathan12343 at gmail.com>
wrote:

> If there aren't any particles, then (in my example) ('CenOstriker',
> 'creation_time') won't be in ds.field_list, so you could do something like:
>
>     if field in ds.field_list:
>         nparticles = ad[field].shape[0]
>     else:
>         nparticles = 0
>
> Nathan
>
>
> On Friday, May 13, 2016, David Collins <dcollins4096 at gmail.com> wrote:
>
>>
>> Cool.  I may try my hand at such an object.
>>
>> The problem with doing something like ad['CenOstriker','creation_time']
>> is that if there are no particles it raises an error, so for smooth flying
>> I'd need to put it in a try/except, but that's not a huge deal.
>>
>>
>> Thanks!
>> d.
>>
>> On Fri, May 13, 2016 at 4:42 PM, Nathan Goldbaum <nathan12343 at gmail.com>
>> wrote:
>>
>>> This uses the ActiveParticleCosmology dataset from yt-project.org/data:
>>>
>>>     import yt
>>>     ds = yt.load('ActiveParticleCosmology/DD0046/DD0046')
>>>     ad = ds.all_data()
>>>     print(ad['CenOstriker', 'creation_time'].shape)
>>>
>>> Which prints out (899755,), so there are 899755 active particles in this
>>> simulation.
>>>
>>> There isn't a convenience function to get the number of each particle
>>> type in the simulation. Adding such a convenience function (or populating
>>> some Dataset attribute with this information when we load the data so we
>>> don't need to make another I/O pass over the dataset) would be a great
>>> addition to yt. There's even a very long-standing issue opened by me about
>>> this...
>>>
>>> https://bitbucket.org/yt_analysis/yt/issues/718
>>>
>>> On Fri, May 13, 2016 at 3:32 PM, David Collins <dcollins4096 at gmail.com>
>>> wrote:
>>>
>>>> Hi, Everybody!
>>>>
>>>> Is there a field or function that totals the number of active
>>>> particles?  I see that I can get it from the grid, but I don't see anything
>>>> for the whole ds.
>>>>
>>>> Thanks,
>>>> d.
>>>>
>>>> --
>>>> -- Sent from a computer.
>>>>
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>>>>
>>>>
>>>
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>>
>>
>> --
>> -- Sent from a computer.
>>
>
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