[yt-users] yt for RAMSES

[Ricarda Beckmann]

Hi Nicolas,

the star ages are indeed a known and unsolved problem in yt when using RAMSES.

Having a quick look at your code it seems fine, you just need one more set of brackets when calling it: ad[('all',’star_age2’)]
Otherwise it looks for the fields “all” and “star_age2” separately. 

Does that help?

Ricarda 

> On 14 Jan 2016, at 14:03, Nicolas Gillet <nicolas.gillet at etu.unistra.fr> wrote:
> 
> Hello,
> 
> I am Nicolas, I am a new YT user. I am working on RAMSES simulations.
> 
> - First I have noted a "bug" (or misunderstand) in the yt.load of RAMSES data.
> It takes all the times of the output as 'code_units' times, which is not the case.
> The output times are negative and I think it needs a FLRW integration to be converted in conventional time.
> Using directly the 'code_units_time' to convert in cgs time is wrong.
> So all the times are false in the loaded yt data, simulation time, particles ages ....
> 
> - My second question is link to the first point. With ramses there is a tool (getstarlist.f90) that extract only the stars in a .txt file, with the ages in Myr with the proper conversion.
> My idea is to load those new data in yt, and creat a new field for particles, with this correct ages.
> With the example I creat a filter to isolate the stars from 'all' particles, and it apear in the derived_field_list.
> But I do not find a way to creat a new field for this filtered particles and even for the 'all' particles.
> 
> I would like to have the possibility to have a field ad['star', 'my_own_ages'] or ad['all', 'my_own_ages'].
> 
> What I have done:
> 
> ### isolate star particles
> def _star(pfilter, data):
>     filter = data['all', 'particle_age'] < 0
>     return filter
> 
> add_particle_filter('star', function=_star, filtered_type='all', requires=['particle_age','particle_identifier'])
> ds.add_particle_filter('star')
> 
> ### stars are correctly created ok
> 
> ### create a global star_age field, not linked to 'all' or 'star'
> def _star_age(field, data):
>     T = data['particle_age'].in_units('Myr') * 0.
>     selec_stars = np.where(data['particle_age'] < 0)[0]
>     T[selec_stars] = Stars[5,:] * yt.units.Myr
>     return T
> 
> ds.add_field('star_age', function=_star_age, units='Myr')
> 
> 
> 
> What I try:
> 
> def _star_age2(field, data):
>     T = data['all','particle_age'].in_units('Myr') * 0.
>     selec_stars = np.where(data['all','particle_age'] < 0) [0]
>     T[selec_stars] = Stars[5,:] * yt.units.Myr
>     return T
> 
> ds.add_field(('all','star_age2'), function=_star_age2, units='Myr')
> 
> ### ('all','star_age2') appear in the derived_field_list but
> 
> ad['all','star_age2'] => YTFieldTypeNotFound: Could not find field 'all' 
> 
> 
> Thank you for your help,
> Nicolas
> 
> 
> 
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