Error when attempting to rename quantified coordinate

[simonkeys]

Renaming of coordinates of a quantified DataArray seems to not work:

import xarray as xr
import pint_xarray

da = xr.DataArray([1, 2, 3], coords=[("x", [1,2,3], {"units": "s"})], attrs={"units": 'm'}).pint.quantify()
da.rename(x='y')

raises the error

KeyError                                  Traceback (most recent call last)
Cell In[9], [line 5](vscode-notebook-cell:?execution_count=9&line=5)
      2 import pint_xarray
      4 da = xr.DataArray([1, 2, 3], coords=[("x", [1,2,3], {"units": "s"})], attrs={"units": 'm'}).pint.quantify()
----> [5](vscode-notebook-cell:?execution_count=9&line=5) da.rename(x='y')

File ~/miniconda3/envs/conda-3.13-srt/lib/python3.13/site-packages/xarray/core/dataarray.py:2594, in DataArray.rename(self, new_name_or_name_dict, **names)
   2591 if utils.is_dict_like(new_name_or_name_dict) or new_name_or_name_dict is None:
   2592     # change dims/coords
   2593     name_dict = either_dict_or_kwargs(new_name_or_name_dict, names, "rename")
-> [2594](~/miniconda3/envs/conda-3.13-srt/lib/python3.13/site-packages/xarray/core/dataarray.py:2594)     dataset = self._to_temp_dataset()._rename(name_dict)
   2595     return self._from_temp_dataset(dataset)
   2596 if utils.hashable(new_name_or_name_dict) and names:
   2597     # change name + dims/coords

File ~/miniconda3/envs/conda-3.13-srt/lib/python3.13/site-packages/xarray/core/dataset.py:4206, in Dataset._rename(self, name_dict, **names)
   4197     if create_dim_coord:
   4198         warnings.warn(
   4199             f"rename {k!r} to {name_dict[k]!r} does not create an index "
   4200             "anymore. Try using swap_dims instead or use set_index "
   (...)   4203             stacklevel=3,
   4204         )
-> [4206](~/miniconda3/envs/conda-3.13-srt/lib/python3.13/site-packages/xarray/core/dataset.py:4206) variables, coord_names, dims, indexes = self._rename_all(
   4207     name_dict=name_dict, dims_dict=name_dict
   4208 )
   4209 return self._replace(variables, coord_names, dims=dims, indexes=indexes)

File ~/miniconda3/envs/conda-3.13-srt/lib/python3.13/site-packages/xarray/core/dataset.py:4161, in Dataset._rename_all(self, name_dict, dims_dict)
   4158 variables, coord_names = self._rename_vars(name_dict, dims_dict)
   4159 dims = self._rename_dims(dims_dict)
-> [4161](~/miniconda3/envs/conda-3.13-srt/lib/python3.13/site-packages/xarray/core/dataset.py:4161) indexes, index_vars = self._rename_indexes(name_dict, dims_dict)
   4162 variables = {k: index_vars.get(k, v) for k, v in variables.items()}
   4164 return variables, coord_names, dims, indexes

File ~/miniconda3/envs/conda-3.13-srt/lib/python3.13/site-packages/xarray/core/dataset.py:4140, in Dataset._rename_indexes(self, name_dict, dims_dict)
   4138     new_coord_names = [name_dict.get(k, k) for k in coord_names]
   4139     indexes.update(dict.fromkeys(new_coord_names, new_index))
-> [4140](~/miniconda3/envs/conda-3.13-srt/lib/python3.13/site-packages/xarray/core/dataset.py:4140)     new_index_vars = new_index.create_variables(
   4141         {
   4142             new: self._variables[old]
   4143             for old, new in zip(coord_names, new_coord_names, strict=True)
   4144         }
   4145     )
   4146     variables.update(new_index_vars)
   4148 return indexes, variables

File ~/miniconda3/envs/conda-3.13-srt/lib/python3.13/site-packages/pint_xarray/index.py:36, in PintIndex.create_variables(self, variables)
     34 index_vars_units = {}
     35 for name, var in index_vars.items():
---> [36](~/miniconda3/envs/conda-3.13-srt/lib/python3.13/site-packages/pint_xarray/index.py:36)     data = conversion.array_attach_units(var.data, self.units[name])
     37     var_units = Variable(var.dims, data, attrs=var.attrs, encoding=var.encoding)
     38     index_vars_units[name] = var_units

KeyError: 'y'

This is with xarray 2025.11.0 and pint-xarray 0.6.0

[keewis]

thanks for the report, @simonkeys. Looks like when writing the tests I was expecting rename to not rename in the units dict, as well. This should be fixed by #351.