issue_comments: 241232491

I agree that it would make sense for xarray.align to unify chunks in dask arrays, but the documentation is actually a little out of date here: dask.array does now do some minimal automatic rechunking (see unify_chunks for details). Also, dask array functions, at least those that use elemwise, do automatically coerce NumPy arrays into dask arrays. So adding a tiny numpy array to a huge dask array does currently do the right thing.

As you can see, the automatic rechunking algorithm that dask.array currently uses is super simple: it only reconciles chunks when one array is unchunked. I'm certainly open to more sophisticated options for automatic rechunking (see https://github.com/dask/dask/issues/111), but either way I'd prefer to keep as much of this logic on the dask side as possible. Ideally, we'd simply call dask.array.unify_chunks passing in the named dimensions for each array.