ds = xr.tutorial.load_dataset("air_temperature") with 0.18 needs engine argument

[scottyhq]

Many notebooks out there start with the line ds = xr.tutorial.load_dataset("air_temperature"). That now gives an error traceback with xarray>=0.18:

Traceback (most recent call last):
  File "/Users/scott/GitHub/zarrdata/./create_zarr.py", line 6, in <module>
    ds = xr.tutorial.load_dataset("air_temperature")
  File "/Users/scott/miniconda3/envs/zarrdata/lib/python3.9/site-packages/xarray/tutorial.py", line 179, in load_dataset
    with open_dataset(*args, **kwargs) as ds:
  File "/Users/scott/miniconda3/envs/zarrdata/lib/python3.9/site-packages/xarray/tutorial.py", line 100, in open_dataset
    ds = _open_dataset(filepath, **kws)
  File "/Users/scott/miniconda3/envs/zarrdata/lib/python3.9/site-packages/xarray/backends/api.py", line 485, in open_dataset
    engine = plugins.guess_engine(filename_or_obj)
  File "/Users/scott/miniconda3/envs/zarrdata/lib/python3.9/site-packages/xarray/backends/plugins.py", line 112, in guess_engine
    raise ValueError("cannot guess the engine, try passing one explicitly")
ValueError: cannot guess the engine, try passing one explicitly

It's an easy fix though, just add ds = xr.tutorial.load_dataset("air_temperature", engine="netcdf4"), new users might be thrown by that though. Also a note that unless the netcdf4 library is explicitly put into the software environment, even adding the engine=netcdf4 can result in an error: "ValueError: unrecognized engine netcdf4 must be one of: ['store', 'zarr']", so I think a minimal environment definition to run would be:

name: xarray-tutorial
channels:
  - conda-forge
dependencies:
  - xarray=0.18
  - pooch=1.3
  - netcdf4=1.5
  - zarr=2.8

[keewis]

thanks for the report, @scottyhq. Please note that while the module is called xarray.tutorial (the same as this repository), it is actually implemented in the main repository. I'll close this and re-open on the main repository. Feel free to continue there.