Hi all, I've adapted yt's gdf_writer.py into a standalone class called pygdf ( https://bitbucket.org/jsoishi/pygdf). I've done this so that any python code can now save data in the gdf format. While doing this, I came across something in the yt gdf frontend that I'm not quite sure I understand. In the grid metadata, yt expects /grid_particle_count to be a 2-D array, but the gdf standard clearly states this should be a 1-D (int64, N) array, where N is the number of grids. Further complicating the issue is the fact that if I create a 1-D array for /grid_particle_count, the failure point in the following script from yt.mods import * pf = load("/tmp/blah.gdf") sp = SlicePlot(pf, 2, "Density") is actually in data_objects/grid_patch.py, not in the gdf frontend itself. The file /tmp/blah.gdf can be generated by running the test.py script in pygdf. The obvious workaround is to simply make /grid_particle_count a 2D array (this is especially so since I'm not actually using particles at the moment), but I'm not sure why this should be so. The total count of particles in N grids seems to be better fit in a 1-D array to me. However, I'd like to understand better what's going on. Any pointers or clarification would be very helpful. Also, any feedback on pygdf would be most welcome! thanks, j