[yt-users] Density / DMDensity

[ｔyuta]

Thanks again! It worked fine.

2017-10-12 10:49 GMT-04:00 Nathan Goldbaum <nathan12343 at gmail.com>:

>
>
> On Thu, Oct 12, 2017 at 9:33 AM, ｔyuta <y0u1t1a5.t at gmail.com> wrote:
>
>> Dear Nathan,
>>
>> The particle filter worked well and I could read the star density from
>> the data. Thanks!
>> Now I want to subtract stellar mass density from Dark_Matter_Density. I
>> was trying to define a new field "only_DM", but it did not work. Could you
>> tell me what is wrong with this?
>>
>> (jupiter notebook session)
>> import yt
>> from yt.data_objects.particle_filters import add_particle_filter
>>
>> def stars(pfilter, data):
>>     filter = data[(pfilter.filtered_type, "particle_type")] == 2
>>     return filter
>>
>> add_particle_filter("stars", function=stars, filtered_type='io',
>>                     requires=["particle_type"])
>>
>> ds.add_particle_filter('stars')
>>
>> def only_DM(field, data):
>>     return data['Dark_Matter_Density'] - data['deposit','stars_density']
>>
>> ds=yt.load(".../redshift00??")
>>
>> ds.add_field(("Dark_Matter_Density", "only_DM_Density"),
>> units="kg/m**3", function=only_DM)
>>
>
> The issue might be here? I think this field needs to be named ('gas',
> 'only_DM_density') - the field entry in a yt field tuple is always a field
> type, not a field name as you've used here. You need to use the 'gas' field
> type because it's defined on the Enzo AMR mesh, which is usually only for
> gas fields.
>
> You might also want to try using a particle filter for the dark matter as
> well, dark matter particles have particle_type == 0.
>
> -Nathan
>
>
>>
>> and the error message appears:
>>
>> YTFieldNotFound: Could not find field '('deposit', 'stars_density')' in redshift00??.
>>
>>
>> Sincerely,
>>
>> Y.T.
>>
>>
>> 2017-10-11 16:24 GMT-04:00 Nathan Goldbaum <nathan12343 at gmail.com>:
>>
>>> OK, in that case I wouldn't try to infer the stellar mass from the
>>> Dark_Matter_Density field (which does include stellar mass despite the
>>> name), instead I would define a particle filter for stars (
>>> http://yt-project.org/doc/analyzing/filtering.html#filterin
>>> g-particle-fields) and then use the new particle type defined by the
>>> filter to create a deposited particle field (
>>> http://yt-project.org/doc/analyzing/fields.html#deposited-p
>>> article-fields).
>>>
>>> There's an example in the docs for how to do this with Tipsy data here:
>>> http://yt-project.org/doc/cookbook/constructing_data_objects
>>> .html#creating-particle-filters
>>>
>>> For Enzo, you should use the particle_type field to create the filter -
>>> star particles in Enzo have particle_type equal to 2. Here's a short worked
>>> example:
>>>
>>> https://gist.github.com/anonymous/acd4007dbff283fc3587a47e8ba41dc3
>>>
>>> Hope that helps! And I hope to hear more from you - your name is
>>> particularly well suited to the yt project ;)
>>>
>>> -Nathan
>>>
>>>
>>> On Wed, Oct 11, 2017 at 12:58 PM, ｔyuta <y0u1t1a5.t at gmail.com> wrote:
>>>
>>>> Yes, it's Enzo data.
>>>>
>>>> 2017-10-11 10:17 GMT-04:00 Nathan Goldbaum <nathan12343 at gmail.com>:
>>>>
>>>>> What simulation code are you working with? From the field names it
>>>>> sounds like Enzo data.
>>>>>
>>>>> On Wed, Oct 11, 2017 at 9:13 AM ｔyuta <y0u1t1a5.t at gmail.com> wrote:
>>>>>
>>>>>> Dear yt-users,
>>>>>>
>>>>>> Hi, I'm a new user of yt. I have a question about the default
>>>>>> 'Density' field and 'Dark_Matter_Density' field. Do they contain stellar
>>>>>> mass? If so, how can I read and subtract stellar mass from the data?
>>>>>>
>>>>>> Sincerely,
>>>>>> Y.T.
>>>>>> _______________________________________________
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>>>>>>
>>>>>
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