Zarr groups (grouped) loader and operations

[itsgifnotjiff]

Is your feature request related to a problem?

I work in geospatial sciences and use Zarr, Xarray, NetCDF etc. but it is at the moment very hard to create a Xarray Dataset that contains multiple grids and dimensions.

Describe the solution you'd like

Ideally I would love to be able to open Zarr store with groups where attributes are preserved and identified by Xarray for easier interoperability with HoloViz and others.

Describe alternatives you've considered

Right now I try and add the groups of a Zarr store one by one as variables but that is hacky and does not necessarily preserve attributes.

Additional context

No response

[keewis]

you might be interested in datatree, then.

@TomNicholas, as we've recently seen an uptake in issues / questions about this, I wonder if we can somehow increase the visibility of datatree? For example, we could mention it in the description of open_dataset's group parameter.

[TomNicholas]

@keewis #7338 mentions datatree, so we could refer people back to there from now on?

[dcherian]

I like the idea of linking to it in the docstring. Doesn't hurt to have more places where people can find info.

[TomNicholas]

For example, we could mention it in the description of open_dataset's group parameter.

We can't really do this because the open_dataset docstring doesn't explicitly include group. I think that's because it's technically a backend-specific kwarg?

Regardless I think this original issue is closed by the recent release of xarray.DataTree.