Error on assign_coords

[rogerkuou]

In xarray_insar_example.ipynb, cell 10-13. If we simplify the script to the following:

ds_pointset = ds_pointset.reset_index("points")
ds_pointset = ds_pointset.assign_coords(points=range(ds_pointset.points.size))
ds_pointset = ds_pointset.reset_coords(("azimuth", "range")) # azimuth and range can be dealt as variables after `points` is defined as new coordinate.

an error occurs on assign_coords:

Output exceeds the [size limit](command:workbench.action.openSettings?[). Open the full output data [in a text editor](command:workbench.action.openLargeOutput?3dffe212-2a91-4ba8-aaed-47fcfd879433)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
/mnt/c/Users/OuKu/Developments/MobyLe/JupyterNB_examples/xarray_insar_example.ipynb Cell 21 in <cell line: 2>()
      [1](vscode-notebook-cell://wsl%2Bubuntu-18.04/mnt/c/Users/OuKu/Developments/MobyLe/JupyterNB_examples/xarray_insar_example.ipynb#Y113sdnNjb2RlLXJlbW90ZQ%3D%3D?line=0) ds_pointset = ds_pointset.reset_index("points")
----> [2](vscode-notebook-cell://wsl%2Bubuntu-18.04/mnt/c/Users/OuKu/Developments/MobyLe/JupyterNB_examples/xarray_insar_example.ipynb#Y113sdnNjb2RlLXJlbW90ZQ%3D%3D?line=1) ds_pointset = ds_pointset.assign_coords(points=range(ds_pointset.points.size))
      [3](vscode-notebook-cell://wsl%2Bubuntu-18.04/mnt/c/Users/OuKu/Developments/MobyLe/JupyterNB_examples/xarray_insar_example.ipynb#Y113sdnNjb2RlLXJlbW90ZQ%3D%3D?line=2) ds_pointset = ds_pointset.reset_coords(("azimuth", "range"))

File ~/miniconda3/envs/mobyle/lib/python3.10/site-packages/xarray/core/common.py:592, in DataWithCoords.assign_coords(self, coords, **coords_kwargs)
    590 data = self.copy(deep=False)
    591 results: dict[Hashable, Any] = self._calc_assign_results(coords_combined)
--> 592 data.coords.update(results)
    593 return data

File ~/miniconda3/envs/mobyle/lib/python3.10/site-packages/xarray/core/coordinates.py:162, in Coordinates.update(self, other)
    160 other_vars = getattr(other, "variables", other)
    161 self._maybe_drop_multiindex_coords(set(other_vars))
--> 162 coords, indexes = merge_coords(
    163     [self.variables, other_vars], priority_arg=1, indexes=self.xindexes
    164 )
    165 self._update_coords(coords, indexes)

File ~/miniconda3/envs/mobyle/lib/python3.10/site-packages/xarray/core/merge.py:566, in merge_coords(objects, compat, join, priority_arg, indexes, fill_value)
    564 collected = collect_variables_and_indexes(aligned)
    565 prioritized = _get_priority_vars_and_indexes(aligned, priority_arg, compat=compat)
--> 566 variables, out_indexes = merge_collected(collected, prioritized, compat=compat)
...
    204     f"{indexes[index_id]!r}"
    205 )

ValueError: cannot set or update variable(s) 'points', which would corrupt the following index built from coordinates 'points', 'azimuth', 'range':
<xarray.core.indexes.PandasMultiIndex object at 0x7f5663d2c040>

According to PR #1 this is not an issue for Francesco. Need to investigate the cause.