Hi all, I'm still struggling in porting the my ZEUS data in spherical coordinates in yt. After many tests, I decided that it would by a good idea to interpolate all my arrays from the spherical (non uniform) grid to an AMR grid in cartesian (it will help me also with other software that accepts only cartesian coordinates). I wrote a python program to create an octree, but it is quite unefficient. Than, I read that it is possible to create an octree with yt. What I REALLY would like to do is to compute the octree, save all grids, all the levels in the GDF format, than with a script open the GDF format and insert in every grid the interpolated density, energy etc... I'm able to create the octree (or at least I think!) using the attached script, but I don't know how to save it in the GDF format. Could you help me? Many thanks, Andrea