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/3731#issuecomment-1234643971,https://api.github.com/repos/pydata/xarray/issues/3731,1234643971,IC_kwDOAMm_X85JlywD,3698640,2022-09-01T18:36:30Z,2022-09-01T18:36:30Z,CONTRIBUTOR,"FWIW I could definitely see use cases for allowing something like this... I have used cumbersome/ugly workarounds to work with variance-covariance matrices etc. So I'm not weighing in on the ""this should raise an error"" debate. I got briefly excited when I saw it *didn't* raise an error, until everything started unraveling 🙃 ","{""total_count"": 2, ""+1"": 1, ""-1"": 0, ""laugh"": 1, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,557257598
https://github.com/pydata/xarray/issues/3731#issuecomment-1234639080,https://api.github.com/repos/pydata/xarray/issues/3731,1234639080,IC_kwDOAMm_X85Jlxjo,3698640,2022-09-01T18:31:08Z,2022-09-01T18:31:08Z,CONTRIBUTOR,"ooh this is a fun one! came across this issue when we stumbled across a pendantic case writing tests (H/T @brews). I expected this to ""fail loudly in the constructor"" but it doesn't. note that currently AFAICT you cannot use positional slicing to achieve an intuitive result - the behavior seems more undefined/unpredictable

```python
# setup
import xarray as xr, pandas as pd, numpy as np
da = xr.DataArray(np.arange(8).reshape(2, 2, 2), coords=[[0, 1], [0, 1], ['a', 'b']], dims=[""ni"", ""ni"", ""shh""])
```
xarray seems to not know it has a problem:
```python
In [4]: da
Out[4]:
<xarray.DataArray (ni: 2, shh: 2)>
array([[[0, 1],
        [2, 3]],

       [[4, 5],
        [6, 7]]])
Coordinates:
  * ni       (ni) int64 0 1
  * shh      (shh) <U1 'a' 'b'
```
slicing (somewhat intuitively? slices along both dims):
```python
In [5]: da.sel(ni=0)
Out[5]:
<xarray.DataArray (shh: 2)>
array([0, 1])
Coordinates:
    ni       int64 0
  * shh      (shh) <U1 'a' 'b'
```
however, positional slicing (and any attempts I've made to handle the repeated dims differently) seems to have undefined behavior:
```python
In [6]: da[0, :, :]  # positional slicing along first dim works as expected(?)
Out[6]:
<xarray.DataArray (ni: 2, shh: 2)>
array([[[0, 1],
        [2, 3]],

       [[4, 5],
        [6, 7]]])
Coordinates:
  * ni       (ni) int64 0 1
  * shh      (shh) <U1 'a' 'b'

In [7]: da[:, 0, :]  # positional slicing along second dim slices both dims
Out[7]:
<xarray.DataArray (shh: 2)>
array([0, 1])
Coordinates:
    ni       int64 0
  * shh      (shh) <U1 'a' 'b'
```","{""total_count"": 2, ""+1"": 2, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,557257598