html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/4079#issuecomment-1434780029,https://api.github.com/repos/pydata/xarray/issues/4079,1434780029,IC_kwDOAMm_X85VhQF9,90008,2023-02-17T15:08:50Z,2023-02-17T15:08:50Z,CONTRIBUTOR,"I know it is ""stale"" but aligning to these ""surprise dimensions"" creates ""late stage"" bugs that are hard to pinpoint.

I'm not sure if it is possible to mark these dimensions as ""unnamed"" and as such, they should be ""merged"" into new ""unnamed"" dimensions that the user isn't tracking at this point in time.

Our workaround have included calling these dimensions something related to the datarray `d1_i`, or simply making small small ""arrays"" a countable number of scalar variables (`d1_min`, `d1_max`) instead of a single array containing two values `d1_limits`.


```python
import xarray as xr
d1 = xr.DataArray(data=[1, 2])
assert 'dim_0' in d1.dims
d2 = xr.DataArray(data=[1, 2, 3])
assert 'dim_0' in d2.dims

xr.Dataset({'d1': d1, 'd2': d2})
```

<details> <summary>Stack trace</summary>

```
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Cell In[2], line 7
      4 d2 = xr.DataArray(data=[1, 2, 3])
      5 assert 'dim_0' in d2.dims
----> 7 xr.Dataset({'d1': d1, 'd2': d2})

File ~/mambaforge/envs/dev/lib/python3.9/site-packages/xarray/core/dataset.py:612, in Dataset.__init__(self, data_vars, coords, attrs)
    609 if isinstance(coords, Dataset):
    610     coords = coords.variables
--> 612 variables, coord_names, dims, indexes, _ = merge_data_and_coords(
    613     data_vars, coords, compat=""broadcast_equals""
    614 )
    616 self._attrs = dict(attrs) if attrs is not None else None
    617 self._close = None

File ~/mambaforge/envs/dev/lib/python3.9/site-packages/xarray/core/merge.py:564, in merge_data_and_coords(data_vars, coords, compat, join)
    562 objects = [data_vars, coords]
    563 explicit_coords = coords.keys()
--> 564 return merge_core(
    565     objects,
    566     compat,
    567     join,
    568     explicit_coords=explicit_coords,
    569     indexes=Indexes(indexes, coords),
    570 )

File ~/mambaforge/envs/dev/lib/python3.9/site-packages/xarray/core/merge.py:741, in merge_core(objects, compat, join, combine_attrs, priority_arg, explicit_coords, indexes, fill_value)
    738 _assert_compat_valid(compat)
    740 coerced = coerce_pandas_values(objects)
--> 741 aligned = deep_align(
    742     coerced, join=join, copy=False, indexes=indexes, fill_value=fill_value
    743 )
    744 collected = collect_variables_and_indexes(aligned, indexes=indexes)
    745 prioritized = _get_priority_vars_and_indexes(aligned, priority_arg, compat=compat)

File ~/mambaforge/envs/dev/lib/python3.9/site-packages/xarray/core/alignment.py:848, in deep_align(objects, join, copy, indexes, exclude, raise_on_invalid, fill_value)
    845     else:
    846         out.append(variables)
--> 848 aligned = align(
    849     *targets,
    850     join=join,
    851     copy=copy,
    852     indexes=indexes,
    853     exclude=exclude,
    854     fill_value=fill_value,
    855 )
    857 for position, key, aligned_obj in zip(positions, keys, aligned):
    858     if key is no_key:

File ~/mambaforge/envs/dev/lib/python3.9/site-packages/xarray/core/alignment.py:785, in align(join, copy, indexes, exclude, fill_value, *objects)
    589 """"""
    590 Given any number of Dataset and/or DataArray objects, returns new
    591 objects with aligned indexes and dimension sizes.
   (...)
    775 
    776 """"""
    777 aligner = Aligner(
    778     objects,
    779     join=join,
   (...)
    783     fill_value=fill_value,
    784 )
--> 785 aligner.align()
    786 return aligner.results

File ~/mambaforge/envs/dev/lib/python3.9/site-packages/xarray/core/alignment.py:573, in Aligner.align(self)
    571 self.assert_no_index_conflict()
    572 self.align_indexes()
--> 573 self.assert_unindexed_dim_sizes_equal()
    575 if self.join == ""override"":
    576     self.override_indexes()

File ~/mambaforge/envs/dev/lib/python3.9/site-packages/xarray/core/alignment.py:472, in Aligner.assert_unindexed_dim_sizes_equal(self)
    470     add_err_msg = """"
    471 if len(sizes) > 1:
--> 472     raise ValueError(
    473         f""cannot reindex or align along dimension {dim!r} ""
    474         f""because of conflicting dimension sizes: {sizes!r}"" + add_err_msg
    475     )

ValueError: cannot reindex or align along dimension 'dim_0' because of conflicting dimension sizes: {2, 3}
```

</details>

cc: @claydugo","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,621078539