Currently 1D slices (x/y/z) and the full 3D output for Grid Functions are both supported output configurations from CarpetX. CarpetX is missing functionality to output 2D planes (xy, xz, yz).

There is a sublety for how the slice is chosen, given the different centering options, some variables likely will not contain data along the x/y/z=0 planes exactly, which is a similar sublety that the 1D output slice must resolve, hopefully these can be resolve consistently.

Also from a discussion with Roland, 2D output is inefficient for a Carpet/CarpetX simulation to output, compared to 1D and 3D. A performance test could be useful in gauging if this feature would be worth implementing/using at all in CarpetX.

TSV (or another text file format) probably makes sense as the starting point, if functional a compressed format like OpenPMD would also be desirable, bringing the 2D CarpetX output features in-line to what was present in Carpet.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2947/carpetx-support-2d-output