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reduce() by multiple dims on groupby object #3402
Description
MCVE Code Sample
# Your code here
import xarray as xr
import numpy as np
url = 'https://data.nodc.noaa.gov/thredds/dodsC/GCOS/monthly_five_degree/19810101-NODC-L3_GHRSST-SSTblend-GLOB_HadSST2-Monthly_FiveDeg_DayNitAvg_19810101_20071231-v01.7-fv01.0.nc'
ds = xr.open_dataset(url, chunks=dict(time=12))
# reduce() directly on dataArray - THIS IS OK
ds.analysed_sst.reduce(np.percentile, dim=('lat','lon'), q=0.5) # ok
# Group by example
rr = ds.analysed_sst.rolling(min_periods=1, center=True, time=5).construct("window")
g = rr.groupby("time.dayofyear")
print(g.dims)
test1d = g.reduce(np.percentile, dim=('time'), q=0.5) # ok
testall = g.reduce(np.percentile, dim=xr.ALL_DIMS, q=0.5) # ok
# .reduce() w/ 2dims on grouby obj not working
test2d = g.reduce(np.nanpercentile, dim=('time','window'), q=0.5)Expected Output
reduced output performed over multiple dimensions (but not xr.ALL_DIMS) on a groupby object
Problem Description
Using .reduce() on a groupby object is only successful when given a single dimensions or by using xr.ALL_DIMS. I wish to apply a reduce on a subset of dims (last line of code above) but gives folowing error:
Traceback (most recent call last):
File "/home/travis/.PyCharmCE2019.2/config/scratches/scratch_20.py", line 13, in <module>
test = g.reduce(np.percentile, dim=('time','window'), q=0.5)
File "/home/travis/.conda/envs/Xarray/lib/python3.7/site-packages/xarray/core/groupby.py", line 800, in reduce
% (dim, self.dims)
ValueError: cannot reduce over dimension ('time', 'window'). expected either xarray.ALL_DIMS to reduce over all dimensions or one or more of ('time', 'lat', 'lon', 'window').
Note: Using reduce() on a subset of dims directly on a xr.DataArray seems fine (line 7).
Activity
dcherian commentedon Oct 15, 2019
🤦♂️ I can't believe we don't test for this. Fix is incoming.
Another groupby.reduce bugfix.
Another groupby.reduce bugfix.
Another groupby.reduce bugfix.
tlogan2000 commentedon Oct 16, 2019
Thx for the quick reply. For info this was working fine with v.0.13.0... it only is occuring since the 0.14.0 upgrade
Another groupby.reduce bugfix. (#3403)