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
505493879,MDU6SXNzdWU1MDU0OTM4Nzk=,3390,xarray.DataArray.where always returns array of float64 regardless of input dtype,6051395,open,0,,,12,2019-10-10T20:29:26Z,2021-03-02T02:42:37Z,,CONTRIBUTOR,,,,"#### MCVE Code Sample
import numpy as np
import xarray as xr

a = xr.DataArray(np.arange(25).reshape(5, 5), dims=('x', 'y'))
print(a.dtype)
    'int32'
a_sub = a.where(a.x + a.y < 4)
a_sub.dtype
    'float64'

#### Expected Output
a_sub should be an xarray of dtype int32

#### Problem Description
The documentation (http://xarray.pydata.org/en/stable/generated/xarray.DataArray.where.html) 
states that return type should be the same type as caller.  However, the return type is always float64

#### Output of ``xr.show_versions()``
INSTALLED VERSIONS
------------------
commit: None
python: 3.7.1 | packaged by conda-forge | (default, Mar 13 2019, 13:32:59) [MSC v.1900 64 bit (AMD64)]
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 45 Stepping 7, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None
LOCALE: None.None
libhdf5: 1.10.4
libnetcdf: 4.6.2

xarray: 0.13.0
pandas: 0.25.1
numpy: 1.17.2
scipy: 1.3.1
netCDF4: 1.4.2
pydap: None
h5netcdf: None
h5py: 2.9.0
Nio: None
zarr: None
cftime: 1.0.3.4
nc_time_axis: None
PseudoNetCDF: None
rasterio: 1.0.22
cfgrib: None
iris: None
bottleneck: None
dask: 2.5.2
distributed: None
matplotlib: 3.1.1
cartopy: 0.17.0
seaborn: 0.9.0
numbagg: None
setuptools: 41.4.0
pip: 19.2.3
conda: None
pytest: None
IPython: 7.8.0
sphinx: None
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/3390/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,issue
508139990,MDExOlB1bGxSZXF1ZXN0MzI4OTkxNjM3,3408,Update where docstring to make return value type more clear,6051395,closed,0,,,3,2019-10-16T22:51:06Z,2019-10-17T14:15:48Z,2019-10-17T14:15:48Z,CONTRIBUTOR,,0,pydata/xarray/pulls/3408,"The where docstring was a little confusing to me.  I misunderstood ""Same type as caller' to mean the values in the xarray not the xarray itself.  I think this small change will clean it up for most users.  Thanks.

<!-- Feel free to remove check-list items aren't relevant to your change -->

 - [x] Closes #3390
 - [x] Passes `black . && mypy . && flake8`
 - [ ] Fully documented, including `whats-new.rst` for all changes and `api.rst` for new API
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/3408/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,pull