volume values in cm3 added to the h5 DAGMC file format

[shimwell]

Is your feature request related to an enhancement? Please describe.

Can we consider adding another attribute to the DAGMC file that is the volume of the each cell/volume

Is your feature request related to a problem? Please describe.

currently i use pydagmc to calculate the volumes of files but it would be more convenient if the volumes were already in the file saved as floats and supported by the format

Describe the solution or outcome you'd like.

Ultimately I want to be able to access these volumes in openmc using the DAGMCUniverse

Describe alternatives you've considered.

pydagmc,but this actually takes a bit of time for big files and requires another install
just updateding cad-to-dagmc so it writes extra info to the h5 file.

Additional Context

perhaps something @pshriwise can consider for xdg
Is this something @akoen and @ebknudsen would be interested in ?

[akoen]

@shimwell I would be onboard with this!

[shimwell]

I am thinking of something like this to add a standard key onto the file. then perhaps openmc.DagmcUniverse in openmc can have method that gets the volume if that key is present.

import h5py

data = {
    "volume_of_material_tags": {
        "mat:material1": 104.34,
        "mat:material2": 23124.34
    }
}

filename = "example.h5"

with h5py.File(filename, "a") as f:
    # Create the top-level group
    group = f.require_group("volume_of_material_tags")

    # Write each key/value as a dataset
    for tag, value in data["volume_of_material_tags"].items():
        # Replace ':' because HDF5 dataset names allow it, but it's sometimes awkward
        dataset_name = tag

        # Delete existing dataset if it already exists
        if dataset_name in group:
            del group[dataset_name]

        # Create dataset storing the float value
        group.create_dataset(dataset_name, data=value)

print("Dictionary written successfully!")

[pshriwise]

I'm on board with this as well as long as, as you indicated Jon, we don't make it a required attribute of the DAGMC file format for backward compatibility purposes. There are other extensions to the format I'm interested in making for the purposes of supporting volumetric MOAB meshes in XDG.