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Groupby exclude dimension #1013
Description
Is there some way to do a groupby operation where some dimension is excluded from the operation, e.g., a vectorized version of something like this:
vertlevels = [ds.vel.sel(nVertLevels=i).groupby('y').mean() for i in ds.nVertLevels]
xavgvel = xr.concat(vertlevels, 'nVertLevels')The application here is to average 3D data in the x coordinate to the unique y coordinates, but not the vertical coordinate.
Thus, we are basically looking for something that allows a coordinate to be excluded from the groupby operation, e.g., in this case the vertical coordinate. Ideally this would also be possible within the context of the groupby_bins operation.
Any ideas on how this should work or a pointer on how to implement this type of operation more cleanly with existing infrastructure is greatly appreciated. This appears to be related to #324 and especially (perhaps identically) #924.
Activity
rabernat commentedon Sep 21, 2016
I explicitly listed this as a TODO in my multidimensional groupby PR (#818):
https://github.com/pydata/xarray/blob/master/xarray/core/groupby.py#L166
It would definitely be useful and is totally doable!
shoyer commentedon Sep 21, 2016
My guess is that this could be implemented pretty quickly on top of #924, which is currently on hold while I finish up #964.
pwolfram commentedon Sep 21, 2016
Thanks @rabernat and @shoyer!
rabernat commentedon Sep 21, 2016
If only we could clone @shoyer!
pwolfram commentedon Sep 21, 2016
Isn't there a git command for that? ;-)
pwolfram commentedon Sep 21, 2016
Thanks for making everyone's life so much better via xarray and for helping us all to contribute to this process @shoyer!
pwolfram commentedon Mar 22, 2017
Note, this issue should be resolvable via #924.
stale commentedon Oct 4, 2020
In order to maintain a list of currently relevant issues, we mark issues as stale after a period of inactivity
If this issue remains relevant, please comment here or remove the
stalelabel; otherwise it will be marked as closed automaticallymax-sixty commentedon Sep 25, 2024
Is this still current?
dcherian commentedon Sep 25, 2024
Yes
dcherian commentedon Apr 29, 2025
#10258 enables this with flox, the classic loopy version will still error.