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

[gso at physics.ucsd.edu]

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.