[yt-dev] GDF PR--call for some feedback

[Matthew Turk]

Hi John,

On Sat, Jul 12, 2014 at 1:48 PM, John Zuhone <jzuhone at 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.

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 at gmail.com
> john.zuhone at nasa.gov
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