issue_comments

```pytb

RuntimeError Traceback (most recent call last) <ipython-input-4-db5c6cefdcdc> in <module> ----> 1 xr.open_dataset(root_data_path+'/MODIS/MOD10C1_Terra/MOD10C1.A2000055.061.2020037182124.hdf')

~/miniconda3/envs/phd_v3/lib/python3.8/site-packages/xarray/backends/api.py in open_dataset(filename_or_obj, group, decode_cf, mask_and_scale, decode_times, autoclose, concat_characters, decode_coords, engine, chunks, lock, cache, drop_variables, backend_kwargs, use_cftime, decode_timedelta) 543 544 with close_on_error(store): --> 545 ds = maybe_decode_store(store) 546 547 # Ensure source filename always stored in dataset object (GH issue #2550)

~/miniconda3/envs/phd_v3/lib/python3.8/site-packages/xarray/backends/api.py in maybe_decode_store(store, lock) 449 450 def maybe_decode_store(store, lock=False): --> 451 ds = conventions.decode_cf( 452 store, 453 mask_and_scale=mask_and_scale,

~/miniconda3/envs/phd_v3/lib/python3.8/site-packages/xarray/conventions.py in decode_cf(obj, concat_characters, mask_and_scale, decode_times, decode_coords, drop_variables, use_cftime, decode_timedelta) 578 encoding = obj.encoding 579 elif isinstance(obj, AbstractDataStore): --> 580 vars, attrs = obj.load() 581 extra_coords = set() 582 file_obj = obj

~/miniconda3/envs/phd_v3/lib/python3.8/site-packages/xarray/backends/common.py in load(self) 121 """ 122 variables = FrozenDict( --> 123 (_decode_variable_name(k), v) for k, v in self.get_variables().items() 124 ) 125 attributes = FrozenDict(self.get_attrs())

~/miniconda3/envs/phd_v3/lib/python3.8/site-packages/xarray/backends/netCDF4_.py in get_variables(self) 397 398 def get_variables(self): --> 399 dsvars = FrozenDict( 400 (k, self.open_store_variable(k, v)) for k, v in self.ds.variables.items() 401 )

~/miniconda3/envs/phd_v3/lib/python3.8/site-packages/xarray/core/utils.py in FrozenDict(args, kwargs) 436 437 def FrozenDict(args, kwargs) -> Frozen: --> 438 return Frozen(dict(*args, kwargs)) 439 440

~/miniconda3/envs/phd_v3/lib/python3.8/site-packages/xarray/backends/netCDF4_.py in <genexpr>(.0) 398 def get_variables(self): 399 dsvars = FrozenDict( --> 400 (k, self.open_store_variable(k, v)) for k, v in self.ds.variables.items() 401 ) 402 return dsvars

~/miniconda3/envs/phd_v3/lib/python3.8/site-packages/xarray/backends/netCDF4_.py in open_store_variable(self, name, var) 374 # netCDF4 specific encoding; save _FillValue for later 375 encoding = {} --> 376 filters = var.filters() 377 if filters is not None: 378 encoding.update(filters)

netCDF4/_netCDF4.pyx in netCDF4._netCDF4.Variable.filters()

netCDF4/_netCDF4.pyx in netCDF4._netCDF4._ensure_nc_success()

RuntimeError: NetCDF: Attempting netcdf-4 operation on netcdf-3 file ```

Description

Any news about this issue? I am facing the same problem and I had to get the calendars by hand... I tried to update xarray but there is still the same issue of missing the ds.time.encoding with open_mfdataset when the dimension to concatenate is the time (because the example from @keewis above works but the concatenation is on x).

Step to reproduce

Here is a simple example to illustrate:

python import xarray as xr ds = xr.tutorial.open_dataset('air_temperature') ds.time.encoding

that gives: python {'source': '/home/lalandmi/.xarray_tutorial_data/air_temperature.nc', 'original_shape': (2920,), 'dtype': dtype('float32'), 'units': 'hours since 1800-01-01', 'calendar': 'standard'}

Let's slipt this dataset and try to read it back with open_mfdataset: python ds.sel(time='2013').to_netcdf('tutorial_air_temperature_2013.nc') ds.sel(time='2014').to_netcdf('tutorial_air_temperature_2014.nc') ds_mf = xr.open_mfdataset('tutorial_air_temperature_*.nc', combine='by_coords') ds_mf.time.encoding that results in an empty dictionary: python {}

Adding some arguments attrs_file=paths[0] with the name of the files didn't change anything for me. Is there any other way or update about this?

Xarray version

Thanks all of you guys to be patient and for your explanations :) Last question: can I archive or delete the mickaellalande/xarray repository on my account now?

Ok I made it back to the branch "patch-1"

Should I update the whatsnewt on pydata/xarray or mickaellalande/xarray? I did it only on mine.

I have no idea if I did the right thing... I changed the 'base' to master on this pull request and also on the repository : mickaellalande/xarray that was created. I don't know if had to do both? Let me know if I'm doing a mess...

I also changed the whatsnew from that repository (mickaellalande/xarray) and wrote: "Fix leap year (http://xarray.pydata.org/en/stable/examples/monthly-means.html) by Mickaël Lalande." under "Documentation".

Hi @max-sixty, thanks for the quick answer. It's my first contribution to Github repository other than mine so I'm not familiar with everything and git too. Can you detail me how to "change the 'base' of your PR to master" and where I "add a change & your name to whatsnew"?

Thanks in advance.