Hi John, I just looked over the GDF format spec you linked to.  It's a nice goal to have a general format, and I know from previous attempts that it can be hard to fit everyone in.  Perhaps for the next spec, you might consider making ``refine_by`` two-dimensional, with one dimension referring to the level index and the other referring to the dimension.  I think that this would be more general.  (Although I'll note that in Maestro, we always ignore the second dimension and just assume all coordinate directions jump by the same amount).


On Sat, Jul 12, 2014 at 2:48 PM, John Zuhone <jzuhone@gmail.com> wrote:
Hi all,

I have a work-in-progress PR in the hopper regarding GDF reading and writing:

https://bitbucket.org/yt_analysis/yt/pull-request/1001/wip-some-gdf-writing-work/diff

What it does is implement direct writing of covering grids to GDF
files (something I've been using in my research, to work with the
resulting files directly in yt) and clobbering existing files with the
same path if the user allows for it.

However, when fiddling around with this I determined that it was
necessary to make GDF more unit-aware. Ultimately, I determined that
changes were needed that would break the standard that we had
determined for the files (http://yt-project.org/gdf.txt).

The two main changes are:

1) Remove "field_to_cgs", and allow the fields to be in whatever units
we wish them to be in the file (which are specified as HDF5
attributes).

2) Add a new top-level group containing the information for
"length","mass", and "time" units. These will be used when the file is
opened up in yt to determine the units.

Since (for now) we do automatic conversion to cgs, that is something
that is still left unimplemented, but otherwise I think this is all to
do for now.

I'm writing the email in case anyone has any suggestions or objections
to the format changes--particularly Jeff or Kacper. We'll obviously
need to document them if they are accepted.

Best,

John

--
John ZuHone

Postdoctoral Researcher
NASA/Goddard Space Flight Center

jzuhone@gmail.com
john.zuhone@nasa.gov
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--
Michael Zingale
Associate Professor

Dept. of Physics & Astronomy • Stony Brook University • Stony Brook, NY 11794-3800
phone:  631-632-8225
e-mail: Michael.Zingale@stonybrook.edu
web: http://www.astro.sunysb.edu/mzingale