Hi Erik,

Thanks for writing.

On Fri, Feb 8, 2013 at 8:42 AM, Erik Schnetter schnetter@cct.lsu.edu wrote:

Matt

(You are presumably speaking of the grid structure stored in HDF5 output files, including in checkpoint files.) What do you intend to do with the grid structure you so obtain?

Yup, that's the structure I'm referring to. I hope to reconstruct the mesh in memory; I have some data I'd like to examine in yt ( http://yt-project.org/ ) which requires understanding the spatial layout of all the grid patches. Right now I'm able to load the data in, make plots, etc, but I'm stuck at a few of the details, and I was hoping to either track it down inside the parsing by perhaps using a second approach to the problem.

If you are interested in the exact grid structure, then yes, this is the correct way to do so. For example, when Carpet reads a grid structure e.g. for recovery, it uses this information.

However, if you e.g. want to visualise data, then there is an alternative. Each dataset (HDF5 component) contains attributes describing the coordinate of its upper left corner as well as the coordinate distance between grid points (grid spacing). This should suffice to correctly combine the datasets you read in, and may be much simpler than parsing the grid structure.

Ah, this will be very helpful! I'll attempt to use this information instead.

Note that the VisIt visualisation toolkit knows how to read Carpet output. You could look at its reader for details.

If you are really interested in parsing the grid structure, then it may be easier to discuss this in person. Are you available on Monday morning 11:00 EST for the Einstein Toolkit telecon? I can explain things there.

I'd love to join in -- thank you for mentioning it!

-Matt

-erik

On Fri, Feb 8, 2013 at 8:15 AM, Matthew Turk matthewturk@gmail.com wrote:

...

Hi all,

I was wondering if someone could point me at how to parse the grid structure information in a Cactus output. I hope this is the right venue for this type of question.

In the output I'm examining, under the "Parameters and Global Attributes" node at root level, there's a "Grid Structure v5" dataset, which contains "grid_superstructure" and "grid_structure". Is parsing the string affiliated with the grid_superstructure component the best way of identifying the spatial extent, dimensions and refinement level of grids in the output?

Thanks very much for any pointers,

Matt _______________________________________________ Users mailing list Users@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/users

-- Erik Schnetter schnetter@cct.lsu.edu http://www.perimeterinstitute.ca/personal/eschnetter/