uninformative error when creating dataset from nameless xarray.DataArray

[rabernat]

I tried to create a holoviews Dataset as follows

data = xr.DataArray(np.random.rand(20,30,40),
                    dims=['z', 'y', 'x'],
                    coords={'z': np.arange(20),
                            'y': np.arange(30),
                            'x': np.arange(40)})
ds = hv.Dataset(data)

I got the error

ValueError: None of the available storage backends were able to support the supplied data format.

Finally I figured out that I needed to provide a name to the dataarray

data = xr.DataArray(np.random.rand(20,30,40),
                    dims=['z', 'y', 'x'],
                    coords={'z': np.arange(20),
                            'y': np.arange(30),
                            'x': np.arange(40)},
                    name='testdata')
ds = hv.Dataset(data)

...and it worked fine.

If the error had said something like "xarray dataarrays must have a name to convert to holoviews datasets", it would have saved me some considerable headache.

[philippjfr]

We need to improve exception handling around the Dataset constructor in general. I've got a proposal around this, which I will describe in detail in a new issue as soon as I get some time to flesh it out.

[jlstevens]

Agreed. We really want better exception messages so I am assigning this issue (tentatively) to the 1.9 milestone.

[philippjfr]

This should now raise the following error:

DataError: If xarray DataArray does not define a name an explicit vdim must be supplied.

XArrayInterface expects gridded data, for more information on supported datatypes see http://holoviews.org/user_guide/Gridded_Datasets.html

[maxibor]

I'm not sure this is related, but I'm getting the same error message here: maxibor/panel-holoviews-volcano#1

[github-actions]

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