issue_comments: 419160841

@djhoese - it would be great if you could track down a more specific example of the issue you are referring to.

Excluding this possible problem with groups, my assessment of the feedback above is that, actually, the only problem is #2233: we can't have multidimensional variables that are also their own dimensions. This is a good thing. It means we have a specific problem to fix.

Right now this is ok: dimensions: x = 4 y = 3 variables: int x(x); int y(y); float data(y, x) But this is not dimensions: x = 4 y = 3 variables: int x(x); float y(y, x); float data(y, x)

Personally I find this to be an incredibly confusing, recursive use of the concept of "dimensions". For me, dimensions should be orthogonal. In the second example, y is a [non-dimension] coordinate, not a dimension! The actual dimension is implicit, some sort of logical y_index. I wish that CF / netCDF had never chosen to accept this as a valid schema. But I admit that perhaps my internal mental model is too wrapped up with xarray!

So the question is: what can we do about it?

I propose the following general outline: - Create a new decoding function to effectively "fix" the recursively defined dimension by renaming y(y, x) into something like y_coordinate(y, x) - Add a new option to open_dataset called decode_recursive_dimension which defaults to False - Raise a more informative error when these types of datasets are encountered which suggests calling open_dataset with decode_recursive_dimension=True

Finally, we might want to raise this upstream with netCDF or CF conventions to try to understand better why this sort of schema is being encouraged.