[yt-users] Test for field

[Matthew Turk]

Hi Elizabeth,

On Sat, Feb 23, 2013 at 3:07 AM, Elizabeth Tasker
<tasker at astro1.sci.hokudai.ac.jp> wrote:
> Hi,
>
> I want to test if a data set at particles. I thought:
>
> pf.has_key("particle_type")
>
> would work, but oddly it doesn't since:
>
> In [17]: pf.has_key("particle_type")
> Out[17]: False
>
> yet:
>
> In [4]: dd = pf.h.all_data()
> In [5]: dd["particle_type"]
> yt : [INFO     ] 2013-02-23 17:00:43,826 Getting particle_type using ParticleIO
> Out[5]: array([11, 11, 11, ..., 11, 11, 11])
>
>
> Shouldn't  pf.has_key("particle_type") be true in this case?

pf has an ill-defined access pattern, so I think the most likely case
is that that will test if it has a conversion factor.

But!  In all codes, all detected fields get added to pf.h.field_list ,
and all derived fields (and non-derived fields) that yt can
conceivably create are in pf.h.derived_field_list .  So you can do:

"particle_type" in pf.h.field_list

for testing this.

-Matt

>
> Elizabeth
>
>
>
>
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