[yt-users] strange particle field behavior

Andrew Myers atmyers at berkeley.edu
Fri May 10 14:41:23 PDT 2013


Hi Britton,

FWIW, I've done things like this before with Orion data and it seems to
work:

def _IsStar(field, data):
    is_star = (data['ParticleMassMsun'] > 0.05).astype('float64')
    return is_star
add_field("IsStar", function=_IsStar, take_log=False, particle_type=True)

Then:

all_data = pf.h.all_data()
print all_data['IsStar']
yt : [INFO     ] 2013-05-10 14:35:27,252 Getting field ParticleMassMsun
from 3611
[ 0.  0.  0.  0.  0.  1.  1.  0.  0.  0.  0.  1.  0.  0.  0.  0.  0.]

Maybe this is something specific to the Enzo frontend?

-Andrew

On Fri, May 10, 2013 at 1:44 PM, Britton Smith <brittonsmith at gmail.com>wrote:

> Hi all,
>
> I am seeing something odd with a field called "IsStarParticle".  This is
> an Enzo field defined in the following way:
>
> def _IsStarParticle(field, data):
>     is_star = (data['creation_time'] > 0).astype('float64')
>     return is_star
>
> When I do the following:
> print pf.h.grids[0]['IsStarParticle']
>
> I get the expected field of 1s and 0s.
>
> When I do this:
> all_data = pf.h.all_data()
> print all_data['IsStarParticle']
>
> I get the values that correspond to the creation_time field.  It does not
> matter in what order I do this.  Whenever I try to access the field from a
> geometric object, I get the actual creation time and not the field I
> expect.  Whenever I access it from a grid object, I get the right thing.
>
> Does anyone know what's going on here?
>
> Britton
>
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> yt-users at lists.spacepope.org
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>
>
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