[yt-users] derived field and TotalQuantity from two sources possible?

[Matthew Turk]

Hi Geoffrey,

You could use the Stream handler to do this.  There's an example on
the blog.  Alternately, you could hack together an IO modification
that handles it, or something.  It could be done.

But, it looks like you are using a private version of Enzo that writes
out a single field at a time into different files, or you are using
modified/processed Enzo outputs.  Either way, it's not something that
we have access to, as yt developers, so we aren't really in a place to
be able to help out that much.  This type of change and fix is
certainly tractable in yt, as it is evident from your final message
that these are really a *single* parameter file that has been split,
but it's not something we have any experience with.

-Matt

On Mon, Jul 18, 2011 at 4:07 PM,  <gso at physics.ucsd.edu> wrote:
> The Enzo files are in different folders separated by fields like:
> RD0015_HI_Density/RD0000.cpuNNNN and RD0015_HII_Density/RD0000.cpuNNNN
>
> So I think I'll just glue the two fields into one and put them in another
> folder.
>
> Thanks for the responses.
>
> From
> G.S.
>
>> Hi Geoffrey,
>>
>> A question: is this actually an Enzo dataset (as in, .cpuNNNN files, with
>> the parameter, hierarchy, etc. files as well), or are you talking about
>> monolothic HDF5 files containing a single field that was created by some
>> third party?  If it's the latter, you're better off just using, say, h5py
>> to
>> read each file in separately, and divide them by each other.  I don't
>> think
>> that the yt machinery is designed for brick-of-bytes HDF5 files (though I
>> may very well be wrong).
>>
>> --B
>>
>> On Mon, Jul 18, 2011 at 5:27 PM, <gso at physics.ucsd.edu> wrote:
>>
>>> Hi,
>>>
>>> I was wondering if it is possible to specify two different sources of
>>> input to create a derived field.  Currently with a single source, I have
>>> a
>>> derived field defined as:
>>>
>>> def _HII_HFraction(field, data):
>>>   return data["HII_Density"]/(data["HI_Density"]+data["HII_Density"])
>>>
>>> add_field("HII_HFraction", function=_HII_HFraction,
>>> units=r"\frac{\rho_{HII}}{\rho_H}")
>>>
>>> And I can access the total quantity in parallel
>>>
>>> pf=load(file)
>>>
>>> dd = pf.h.all_data()
>>>
>>> dd.quantities["TotalQuantity"]("HII_HFraction")[0]
>>>
>>> But I'm dealing with
>>>
>>> pf1=load(file1)
>>> pf2=load(file2)
>>>
>>> pf1 has the HI_Density field data and pf2 has the HII_Density field
>>> data.
>>> Is there a way to create a derived field and use TotalQuantity to
>>> operate
>>> on the data in parallel?
>>>
>>> From
>>> G.S.
>>>
>>> PS. I guess my alternative is to glue the two HDF5 files into one, but
>>> want to avoid it if possible.
>>>
>>>
>>> _______________________________________________
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>>> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>>>
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