issues: 386515973

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386515973 MDU6SXNzdWUzODY1MTU5NzM= 2586 Zarr loading from ZipStore gives error on default arguments 5191106 closed 0     5 2018-12-02T01:28:24Z 2019-01-17T23:49:07Z 2019-01-17T02:20:28Z NONE      

(This is not too much of a problem, but it would probably be a reasonably easy fix) ```python import xarray as xr import zarr

ds = xr.Dataset({'foo': [2,3,4], 'bar': ('x', [1, 2]), 'baz': 3.14})

ds.to_zarr(zarr.ZipStore("test.zarr")) print(xr.open_zarr(zarr.ZipStore("test.zarr"))) This gives the following error:--------------------------------------------------------------------------- ValueError Traceback (most recent call last) <ipython-input-1-c68e53adfa79> in <module> 5 6 ds.to_zarr(zarr.ZipStore("test.zarr")) ----> 7 print(xr.open_zarr(zarr.ZipStore("test.zarr")))

~/.local/lib/python3.7/site-packages/xarray/backends/zarr.py in open_zarr(store, group, synchronizer, auto_chunk, decode_cf, mask_and_scale, decode_times, concat_characters, decode_coords, drop_variables) 424 zarr_store = ZarrStore.open_group(store, mode=mode, 425 synchronizer=synchronizer, --> 426 group=group) 427 ds = maybe_decode_store(zarr_store) 428

~/.local/lib/python3.7/site-packages/xarray/backends/zarr.py in open_group(cls, store, mode, synchronizer, group) 236 "#installation" % min_zarr) 237 zarr_group = zarr.open_group(store=store, mode=mode, --> 238 synchronizer=synchronizer, path=group) 239 return cls(zarr_group) 240

~/.local/lib/python3.7/site-packages/zarr/hierarchy.py in open_group(store, mode, cache_attrs, synchronizer, path) 1111 err_contains_array(path) 1112 elif not contains_group(store, path=path): -> 1113 err_group_not_found(path) 1114 1115 elif mode == 'w':

~/.local/lib/python3.7/site-packages/zarr/errors.py in err_group_not_found(path) 27 28 def err_group_not_found(path): ---> 29 raise ValueError('group not found at path %r' % path) 30 31

ValueError: group not found at path '' Instead, one has to usepython xr.open_zarr(zarr.ZipStore("test.zarr"), group='/') `` When using a dictionary as store (e.g. when usingds.to_zarr('test_zarr')), thisgroup='/'is unnecessary when loading it again, but everything still works when using it anyway. So I'd propose changing the default value of the group argument to'/'`, so the ZipStore (and probably also the other stores) will work by default as well.

 
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