issues: 1120378011

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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
1120378011 I_kwDOAMm_X85Cx5yb 6227 [Bug]: Dataset.where(x, drop=True) behaves inconsistent 43316012 closed 0     0 2022-02-01T08:40:30Z 2022-06-12T22:06:51Z 2022-06-12T22:06:51Z COLLABORATOR      

What happened?

I tried to reduce some dimensions using where (sel did not work in this case) and shorten the dimensions with "drop=True". This works fine on DataArrays and Datasets with only a single dimension but fails as soon as you have a Dataset with two dimensions on different variables. The dimensions are left untouched and you have NaNs in the data, just as if you were using "drop=False" (see example).

I am actually not sure what the expected behavior is, maybe I am wrong and it is correct due to some broadcasting rules?

What did you expect to happen?

I expected that relevant dims are shortened. If the ds.where with "drop=False" all variables along a dimenions have some NaNs, then using "drop=True" I expect these dimensions to be shortened and the NaNs removed.

Minimal Complete Verifiable Example

```python import xarray as xr

this works

ds = xr.Dataset({"a": ("x", [1, 2 ,3])}) ds.where(ds > 2, drop=True)

returns:

<xarray.Dataset>

Dimensions: (x: 1)

Dimensions without coordinates: x

Data variables:

a (x) float64 3.0

this doesn't

ds = xr.Dataset({"a": ("x", [1, 2 ,3]), "b": ("y", [2, 3, 4])}) ds.where(ds > 2, drop=True)

returns:

<xarray.Dataset>

Dimensions: (x: 3, y: 3)

Dimensions without coordinates: x, y

Data variables:

a (x) float64 nan nan 3.0

b (y) float64 nan 3.0 4.0

```

Relevant log output

No response

Anything else we need to know?

No response

Environment

INSTALLED VERSIONS

commit: None python: 3.9.1 (default, Jan 13 2021, 15:21:08) [GCC 4.8.5 20150623 (Red Hat 4.8.5-44)] python-bits: 64 OS: Linux OS-release: 3.10.0-1160.49.1.el7.x86_64 machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: ('en_US', 'UTF-8') libhdf5: 1.12.0 libnetcdf: 4.7.4

xarray: 0.20.2 pandas: 1.3.5 numpy: 1.21.5 scipy: 1.7.3 netCDF4: 1.5.8 pydap: None h5netcdf: None h5py: None Nio: None zarr: None cftime: 1.5.1.1 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: None dask: None distributed: None matplotlib: 3.5.1 cartopy: None seaborn: None numbagg: None fsspec: None cupy: None pint: None sparse: None setuptools: 49.2.1 pip: 22.0.2 conda: None pytest: 6.2.5 IPython: 8.0.0 sphinx: None

 
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   completed 13221727 issue

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