issues: 565626748

This data as json

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
565626748 MDU6SXNzdWU1NjU2MjY3NDg= 3770 `where` ignores incorrectly typed arguments 5635139 closed 0     5 2020-02-15T00:24:37Z 2020-03-07T04:38:12Z 2020-03-07T04:38:12Z MEMBER      

MCVE Code Sample

I optimistically tried passing a lambda to where* to avoid another .pipe. To my surprise it ran! But unfortunately it just ignored the lambda, as though all values were True.

```python

In [1]: import xarray as xr

In [2]: import numpy as np

In [3]: da = xr.DataArray(np.random.rand(2,3))

In [4]: da.where(da > 0.5)
Out[4]: <xarray.DataArray (dim_0: 2, dim_1: 3)> array([[ nan, 0.71442406, nan], [0.55748705, nan, nan]]) Dimensions without coordinates: dim_0, dim_1

this should fail!

In [5]: da.where(lambda x: x > 0.5)
Out[5]: <xarray.DataArray (dim_0: 2, dim_1: 3)> array([[0.26085668, 0.71442406, 0.05816167], [0.55748705, 0.15293073, 0.12766453]]) Dimensions without coordinates: dim_0, dim_1 ```

Expected Output

Raise a TypeError when passed the lambda

* (maybe that could work, but separate discussion)

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.6.8 (default, Aug 7 2019, 17:28:10) [...] python-bits: 64 OS: Linux OS-release: [...] machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.utf8 LOCALE: en_US.UTF-8 libhdf5: 1.10.4 libnetcdf: None xarray: 0.14.1 pandas: 0.25.3 numpy: 1.18.1 scipy: 1.4.1 netCDF4: None pydap: None h5netcdf: None h5py: 2.10.0 Nio: None zarr: None cftime: None nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: None dask: None distributed: None matplotlib: 3.1.2 cartopy: None seaborn: 0.10.0 numbagg: None setuptools: 45.0.0 pip: 20.0.2 conda: None pytest: 5.3.2 IPython: 7.11.1 sphinx: 2.3.1 
{
    "url": "https://api.github.com/repos/pydata/xarray/issues/3770/reactions",
    "total_count": 0,
    "+1": 0,
    "-1": 0,
    "laugh": 0,
    "hooray": 0,
    "confused": 0,
    "heart": 0,
    "rocket": 0,
    "eyes": 0
}
   completed 13221727 issue

Links from other tables