Hello,
Time to drag this up from the dead...
I am currently in the process of making my simulation code write GDF files, and also write a frontend to read them and provide some extra goodies for our code.
Having had a look over this thread and the associated PR, the units top level block sounds useful. Are there plans to add it to the standard document? Is it documented anywhere else?
Stuart
On 15 July 2014 23:35, John ZuHone jzuhone@gmail.com... wrote:
After looking at this some more I've discovered a couple of other wrinkles.
My first thought was to set the dataset units (length, time, mass, etc.) for backup GDF files to be equal to that of the parent dataset, so there's consistency there. However, I then realized that most fields written to backup files would be in cgs, not code units. If any of these fields have aliases (like "density", "velocity_x", etc.), then they will get converted "to cgs" using the conversion factors even if they don't need to be (e.g., they already are in cgs).
So, the backup file could have code units equal to cgs, which would relieve this problem but would leave its code units inconsistent with that of the parent file, or we could find some way to keep the underlying code units of the files the same but prevent this conversion from happening (either by removing the aliases altogether from the GDF frontend or some other procedure).
Would appreciate feedback on this.
On Jul 14, 2014, at 1:49 PM, Matthew Turk matthewturk@gmail.com... wrote:
Hi John,
On Sat, Jul 12, 2014 at 1:48 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-...
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.
I'm in favor of both of these things, along with MikeZ's suggestion about refine by. I think we should call this a 1.1 standard, and then we can evaluate a few other big holes with a 2.0 in the future.
We should also probably allow units like B-field, velocity, etc, as these have in the past had odd, non-conforming properties.
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
yt-dev mailing list yt-dev@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org...
yt-dev mailing list yt-dev@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org...
yt-dev mailing list yt-dev@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org...