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
937266282,MDU6SXNzdWU5MzcyNjYyODI=,5578,Specify minimum versions in setup.cfg,2448579,open,0,,,2,2021-07-05T17:25:03Z,2022-01-09T03:33:38Z,,MEMBER,,,,See https://github.com/pydata/xarray/issues/5342#issuecomment-873660034,"{""url"": ""https://api.github.com/repos/pydata/xarray/issues/5578/reactions"", ""total_count"": 1, ""+1"": 1, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,issue
937264431,MDExOlB1bGxSZXF1ZXN0NjgzODQ5MjQ5,5577,Faster unstacking to sparse,2448579,closed,0,,,4,2021-07-05T17:20:59Z,2021-12-03T16:38:51Z,2021-12-03T16:38:49Z,MEMBER,,0,pydata/xarray/pulls/5577,"<!-- Feel free to remove check-list items aren't relevant to your change -->

- [x] Tests added
- [x] Passes `pre-commit run --all-files`
- [x] User visible changes (including notable bug fixes) are documented in `whats-new.rst`

From 7s to 25 ms and 3.5GB to 850MB memory usage =) by passing the coordinate locations directly to the sparse constructor.
```
asv run -e --bench unstacking.UnstackingSparse.time_unstack_to_sparse  --cpu-affinity=3 HEAD
[  0.00%] · For xarray commit c9251e1c <sparse-unstack>:
[  0.00%] ·· Building for conda-py3.8-bottleneck-dask-distributed-netcdf4-numpy-pandas-scipy-sparse
[  0.00%] ·· Benchmarking conda-py3.8-bottleneck-dask-distributed-netcdf4-numpy-pandas-scipy-sparse
[  0.01%] ··· Running (unstacking.UnstackingSparse.time_unstack_to_sparse_2d--)..
[  0.02%] ··· unstacking.UnstackingSparse.time_unstack_to_sparse_2d    623±30μs
[  0.02%] ··· unstacking.UnstackingSparse.time_unstack_to_sparse_3d    22.8±2ms
[  0.06%] ··· unstacking.UnstackingSparse.peakmem_unstack_to_sparse_2d    793M
[  0.06%] ··· unstacking.UnstackingSparse.peakmem_unstack_to_sparse_3d    794M


[  0.04%] · For xarray commit 80905135 <main>:
[  0.04%] ·· Building for conda-py3.8-bottleneck-dask-distributed-netcdf4-numpy-pandas-scipy-sparse..
[  0.04%] ·· Benchmarking conda-py3.8-bottleneck-dask-distributed-netcdf4-numpy-pandas-scipy-sparse
[  0.05%] ··· Running (unstacking.UnstackingSparse.time_unstack_to_sparse_2d--)..
[  0.06%] ··· unstacking.UnstackingSparse.time_unstack_to_sparse_2d    596±30ms
[  0.06%] ··· unstacking.UnstackingSparse.time_unstack_to_sparse_3d    7.72±0.1s
[  0.02%] ··· unstacking.UnstackingSparse.peakmem_unstack_to_sparse_2d    867M
[  0.02%] ··· unstacking.UnstackingSparse.peakmem_unstack_to_sparse_3d    3.56G
```

cc @bonnland","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/5577/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,pull