id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
1193163400,I_kwDOAMm_X85HHjqI,6442,KeyError(key) when using sel to slice DataArray (pandas 1.4.1; xarray 2022.3.0 ),99778602,closed,0,,,2,2022-04-05T13:37:05Z,2022-04-06T01:12:33Z,2022-04-06T01:12:33Z,NONE,,,,"### What is your issue?

After using xr.open_dataset(xxx.nc4)， I got a DataArray like this:

ln [153]: ds.SpeciesConc_NO2
Out[153]: 
<xarray.DataArray 'SpeciesConc_NO2' (time: 1, lev: 47, lat: 91, lon: 144)>
[615888 values with dtype=float32]
Coordinates:
  * time     (time) datetime64[ns] 2020-05-01T12:00:00
  * lev      (lev) float64 0.9925 0.9775 0.9625 ... 0.0004141 0.0001387 3.8e-05
  * lat      (lat) float64 -89.5 -88.0 -86.0 -84.0 -82.0 ... 84.0 86.0 88.0 89.5
  * lon      (lon) float64 -180.0 -177.5 -175.0 -172.5 ... 172.5 175.0 177.5
Attributes:
    long_name:         Dry mixing ratio of species NO2
    units:             mol mol-1 dry
    averaging_method:  time-averaged

Then I executed ""ds.SpeciesConc_NO2.sel(lev=0.9925)"", KeyError occured like this:

ln [154]: ds.SpeciesConc_NO2.sel(lev=0.9925)
Traceback (most recent call last):

  File ""C:\Anaconda3\lib\site-packages\pandas\core\indexes\base.py"", line 3621, in get_loc
    return self._engine.get_loc(casted_key)

  File ""pandas\_libs\index.pyx"", line 136, in pandas._libs.index.IndexEngine.get_loc

  File ""pandas\_libs\index.pyx"", line 163, in pandas._libs.index.IndexEngine.get_loc

  File ""pandas\_libs\hashtable_class_helper.pxi"", line 1533, in pandas._libs.hashtable.Float64HashTable.get_item

  File ""pandas\_libs\hashtable_class_helper.pxi"", line 1542, in pandas._libs.hashtable.Float64HashTable.get_item

KeyError: 0.9925


The above exception was the direct cause of the following exception:

Traceback (most recent call last):

  File ""C:\Users\li\AppData\Local\Temp/ipykernel_10768/2316184327.py"", line 1, in <module>
    ds.SpeciesConc_NO2.sel(lev=0.9925)

  File ""C:\Anaconda3\lib\site-packages\xarray\core\dataarray.py"", line 1329, in sel
    ds = self._to_temp_dataset().sel(

  File ""C:\Anaconda3\lib\site-packages\xarray\core\dataset.py"", line 2501, in sel
    pos_indexers, new_indexes = remap_label_indexers(

  File ""C:\Anaconda3\lib\site-packages\xarray\core\coordinates.py"", line 421, in remap_label_indexers
    pos_indexers, new_indexes = indexing.remap_label_indexers(

  File ""C:\Anaconda3\lib\site-packages\xarray\core\indexing.py"", line 121, in remap_label_indexers
    idxr, new_idx = index.query(labels, method=method, tolerance=tolerance)

  File ""C:\Anaconda3\lib\site-packages\xarray\core\indexes.py"", line 241, in query
    indexer = self.index.get_loc(label_value)

  File ""C:\Anaconda3\lib\site-packages\pandas\core\indexes\base.py"", line 3623, in get_loc
    raise KeyError(key) from err

KeyError: 0.9925
 
However, it works when executing similar command on other Coordinates, for example, when run ""ds.SpeciesConc_NO2.sel(lon=0)"", results show like this:

<xarray.DataArray 'SpeciesConc_NO2' (time: 1, lev: 47, lat: 91)>
array([[[2.102885e-13, 2.105525e-13, ..., 2.255533e-12, 2.279446e-12],
        [2.113857e-13, 2.110841e-13, ..., 2.129459e-12, 2.182470e-12],
        ...,
        [2.121348e-10, 2.121348e-10, ..., 1.698668e-12, 1.698668e-12],
        [1.997791e-10, 1.997791e-10, ..., 1.914198e-13, 1.914198e-13]]],
      dtype=float32)
Coordinates:
  * time     (time) datetime64[ns] 2020-05-01T12:00:00
  * lev      (lev) float64 0.9925 0.9775 0.9625 ... 0.0004141 0.0001387 3.8e-05
  * lat      (lat) float64 -89.5 -88.0 -86.0 -84.0 -82.0 ... 84.0 86.0 88.0 89.5
    lon      float64 0.0
Attributes:
    long_name:         Dry mixing ratio of species NO2
    units:             mol mol-1 dry
    averaging_method:  time-averaged

I wonder why slicing with ""lev"" can't work here, and how to fix the problem? ","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/6442/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue