Stephan Hoyer

I'm excited to see this coming together! I would be happy to advise as well... Side note: at some point, this would probably be worth adding to Xarray's official roadmap.

@martinitus raises a really interesting point about tags vs hierarchical structures over in https://github.com/pydata/xarray/issues/1092#issuecomment-868324949 > However, one point I didn't see in the discussion is the following: > > Hierarchical...

This sounds great to me! I don't think we need support for setting multiple indexes at once in a single method call. You can call `set_xindex` multiple times for that...

I agree, I think only setting a few indexes at a time would be normal. If we eventually need convenience methods for setting multiple indexes we can add those later.

What happens if you open multiple files with `open_mfdataset()`, e.g., for both January and February. Does it result in a dataset with the right dimensions on each variable?

> I stand corrected. in 0.10.1, I also see the Time variable getting added to refBottomDepth when I open multiple files. So maybe this is not in fact a new...

The logic for determining which variables to concatenate is in the `_calc_concat_over` helper function: https://github.com/pydata/xarray/blob/539fb4a98d0961c281daa5474a8e492a0ae1d8a2/xarray/core/concat.py#L146 Only `"different"` is supposed to load variables into memory to determine which ones to concatenate....

> Specifically, what should the default behavior of concat() be, when both datasets include a variable that does not include the concatenation dimension? Currently, the concat dimension is added, and...

> UPDATE: @shoyer it could be that unit tests are failing because, as your final example shows, you get an error for data_vars='minimal' if _any_ variables have different values across...

Hi Edward, good to hear from you! netCDF does support user-defined types, but unfortunately it can’t read user defined types written by h5py. That’s all I intended to imply with...