Quickstart example doesn't work

[alexgleith]

I tried the quickstart example, here: https://nrt.readthedocs.io/en/latest/quickstart.html

Code looks like this:

from nrt.monitor.ewma import EWMA
from nrt import data

# load example mask
mask = (data.romania_forest_cover_percentage() > 20).astype('int')

# Instantiate
nrt_class = EWMA(
    mask=mask,
    trend=True,
    harmonic_order=3,
    sensitivity=2
)

# load example xarray
s2_cube = data.romania_20m()
history = s2_cube.B3.sel(slice(None, '2019-01-01'))
monitor = s2_cube.B3.sel(slice('2019-01-01', None))

# Fitting
nrt_class.fit(dataarray=history)

# Dump model
nrt_class.to_netcdf('model.nc')

This crashes on the line history = s2_cube.B3.sel(slice(None, '2019-01-01')) with the error:

[1642](https://untitled+.vscode-resource.vscode-cdn.net/opt/homebrew/lib/python3.11/site-packages/xarray/core/dataarray.py:1642)     Dimensions without coordinates: points
   [1643](https://untitled+.vscode-resource.vscode-cdn.net/opt/homebrew/lib/python3.11/site-packages/xarray/core/dataarray.py:1643)     """
-> [1644](https://untitled+.vscode-resource.vscode-cdn.net/opt/homebrew/lib/python3.11/site-packages/xarray/core/dataarray.py:1644)     ds = self._to_temp_dataset().sel(
   [1645](https://untitled+.vscode-resource.vscode-cdn.net/opt/homebrew/lib/python3.11/site-packages/xarray/core/dataarray.py:1645)         indexers=indexers,
   [1646](https://untitled+.vscode-resource.vscode-cdn.net/opt/homebrew/lib/python3.11/site-packages/xarray/core/dataarray.py:1646)         drop=drop,
...
    [195](https://untitled+.vscode-resource.vscode-cdn.net/opt/homebrew/lib/python3.11/site-packages/xarray/namedarray/utils.py:195)     raise ValueError(
    [196](https://untitled+.vscode-resource.vscode-cdn.net/opt/homebrew/lib/python3.11/site-packages/xarray/namedarray/utils.py:196)         f"cannot specify both keyword and positional arguments to .{func_name}"
    [197](https://untitled+.vscode-resource.vscode-cdn.net/opt/homebrew/lib/python3.11/site-packages/xarray/namedarray/utils.py:197)     )

ValueError: the first argument to .sel must be a dictionary

I'm running using xarray version 2024.6.0, but also tested with an older version. Both crashed with the same error.

[loicdtx]

Thanks for reporting this @alexgleith

Did you install nrt from pypi of from a local copy?

The reason I'm asking is because large binary files are tracked with git lfs in the repo. When the repository is cloned without lfs, these files are silently ignored (or git only downloads a pointer instead of the actual file).

[alexgleith]

Ah, from PyPI.

Are the files very large?

[alexgleith]

Also, this crash doesn't look like it's caused by missing data...

[loicdtx]

Okay, I was able to reproduce and identify the issue.

history = s2_cube.B3.sel(time=slice(None, '2019-01-01'))
monitor = s2_cube.B3.sel(time=slice('2019-01-01', None))

must be used instead of:

history = s2_cube.B3.sel(slice(None, '2019-01-01'))
monitor = s2_cube.B3.sel(slice('2019-01-01', None))

[alexgleith]

Of course, yep! Sorry, I should habe been able to figure that out too! haha

[alexgleith]

Ok, now it works, but crashes on nrt_class.fit(dataarray=history), which may be a Python 3.11 issue. I reported this in #10