issue_comments: 540182562

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https://github.com/pydata/xarray/issues/2944#issuecomment-540182562 https://api.github.com/repos/pydata/xarray/issues/2944 540182562 MDEyOklzc3VlQ29tbWVudDU0MDE4MjU2Mg== 2448579 2019-10-09T20:36:55Z 2019-10-09T20:36:55Z MEMBER

So that has been fixed on master somehow but

python da = xr.DataArray(np.arange(12).reshape(3, 4), dims=['x', 'y'], coords={'x': [0, 1, 1], 'x2': ('x', ['a', 'b', 'c']), 'x3': ('x', [4, 5, 6])}) da.groupby("x").mean("x") gives <xarray.DataArray (x: 2, y: 4)> array([[0., 1., 2., 3.], [6., 7., 8., 9.]]) Coordinates: * x (x) int64 0 1 Dimensions without coordinates: y

i.e coordinate x3 has been dropped though the mean along x is meaningful. This is consistent with the behaviour of reduce e.g. ``` python da.mean("x")

<xarray.DataArray (y: 4)> array([4., 5., 6., 7.]) Dimensions without coordinates: y ```

What would be the best way to implement reductions for non-dim coords? Add a reduce_coords kwarg?

 
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