issues: 869948050

This data as json

id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
869948050 MDU6SXNzdWU4Njk5NDgwNTA= 5230 Same files in open_mfdataset() unclear error message 57914115 closed 0     3 2021-04-28T13:26:59Z 2021-04-30T12:41:17Z 2021-04-30T12:41:17Z CONTRIBUTOR      

When using xr.open_mfdataset() with two exact same files by mistake, it causes an unclear error message

What happened:

With of course the time dimension existing :

python ds=xr.open_mfdataset(["some_file.nc","some_file.nc"],concat_dim="time",engine="netcdf4")

```python

ValueError Traceback (most recent call last)

~/.local/src/miniconda/envs/minireobs/lib/python3.8/site-packages/xarray/backends/api.py in open_mfdataset(paths, chunks, concat_dim, compat, preprocess, engine, lock, data_vars, coords, combine, parallel, join, attrs_file, **kwargs) 966 # Redo ordering from coordinates, ignoring how they were ordered 967 # previously --> 968 combined = combine_by_coords( 969 datasets, 970 compat=compat,

~/.local/src/miniconda/envs/minireobs/lib/python3.8/site-packages/xarray/core/combine.py in combine_by_coords(datasets, compat, data_vars, coords, fill_value, join, combine_attrs) 762 concatenated_grouped_by_data_vars = [] 763 for vars, datasets_with_same_vars in grouped_by_vars: --> 764 combined_ids, concat_dims = _infer_concat_order_from_coords( 765 list(datasets_with_same_vars) 766 )

~/.local/src/miniconda/envs/minireobs/lib/python3.8/site-packages/xarray/core/combine.py in _infer_concat_order_from_coords(datasets) 106 107 if len(datasets) > 1 and not concat_dims: --> 108 raise ValueError( 109 "Could not find any dimension coordinates to use to " 110 "order the datasets for concatenation"

ValueError: Could not find any dimension coordinates to use to order the datasets for concatenation ``` What you expected to happen: A warning saying that we are using the same dataset ? A more explicit error message (exact same dimensions) ? No error and no concatenation, remove duplicated datasets?

Environment:

Output of <tt>xr.show_versions()</tt> INSTALLED VERSIONS ------------------ commit: None python: 3.8.5 (default, Sep 4 2020, 07:30:14) [GCC 7.3.0] python-bits: 64 OS: Linux OS-release: 5.4.0-72-generic machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: fr_FR.UTF-8 LOCALE: fr_FR.UTF-8 libhdf5: 1.10.4 libnetcdf: 4.7.3 xarray: 0.17.0 pandas: 1.1.1 numpy: 1.19.2 scipy: 1.5.2 netCDF4: 1.5.3 pydap: None h5netcdf: None h5py: None Nio: None zarr: None cftime: 1.2.1 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: None dask: 2021.04.0 distributed: 2021.04.0 matplotlib: 3.3.1 cartopy: None seaborn: None numbagg: None pint: None setuptools: 49.6.0.post20200814 pip: 20.2.2 conda: None pytest: 6.1.1 IPython: 7.18.1 sphinx: None 
{
    "url": "https://api.github.com/repos/pydata/xarray/issues/5230/reactions",
    "total_count": 0,
    "+1": 0,
    "-1": 0,
    "laugh": 0,
    "hooray": 0,
    "confused": 0,
    "heart": 0,
    "rocket": 0,
    "eyes": 0
}
   completed 13221727 issue

Links from other tables