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
554785150,MDU6SXNzdWU1NTQ3ODUxNTA=,3722,How to plot boolean vector with current xarray,5948670,closed,0,,,3,2020-01-24T15:00:44Z,2020-04-03T23:19:23Z,2020-04-03T23:19:23Z,CONTRIBUTOR,,,,"Dear all,

I'm trying to plot a vector with bool data. It used to work with xarray version 0.10.7 in an old setup, but it isn't working anymore. Am I doing something wrong or is there something new to consider? 

I'm not hundred percent sure, if this problem is due to changes in xarray, numpy or something else

#### Code example
```python
import xarray
xarray.DataArray([True, False]).plot()
```

#### Expected Output
A plot with a line from 1 to 0.


#### Problem Description
However, I get this error:
```
TypeError                                 Traceback (most recent call last)
<ipython-input-22-d911786d1072> in <module>
----> 1 xarray.DataArray([True, False]).plot()

~/python_venvs/python3/py3_18.04/lib/python3.6/site-packages/xarray/plot/plot.py in __call__(self, **kwargs)
    463 
    464     def __call__(self, **kwargs):
--> 465         return plot(self._da, **kwargs)
    466 
    467     @functools.wraps(hist)

~/python_venvs/python3/py3_18.04/lib/python3.6/site-packages/xarray/plot/plot.py in plot(darray, row, col, col_wrap, ax, hue, rtol, subplot_kws, **kwargs)
    200     kwargs[""ax""] = ax
    201 
--> 202     return plotfunc(darray, **kwargs)
    203 
    204 

~/python_venvs/python3/py3_18.04/lib/python3.6/site-packages/xarray/plot/plot.py in line(darray, row, col, figsize, aspect, size, ax, hue, x, y, xincrease, yincrease, xscale, yscale, xticks, yticks, xlim, ylim, add_legend, _labels, *args, **kwargs)
    321         yplt_val = yplt.values
    322 
--> 323     _ensure_plottable(xplt_val, yplt_val)
    324 
    325     primitive = ax.plot(xplt_val, yplt_val, *args, **kwargs)

~/python_venvs/python3/py3_18.04/lib/python3.6/site-packages/xarray/plot/utils.py in _ensure_plottable(*args)
    510         ):
    511             raise TypeError(
--> 512                 ""Plotting requires coordinates to be numeric ""
    513                 ""or dates of type np.datetime64, ""
    514                 ""datetime.datetime, cftime.datetime or ""

TypeError: Plotting requires coordinates to be numeric or dates of type np.datetime64, datetime.datetime, cftime.datetime or pd.Interval.
```


#### Output of ``xr.show_versions()`` in the setup that is not working
<details>
INSTALLED VERSIONS
------------------
commit: None
python: 3.6.7 (default, Oct 22 2018, 11:32:17) 
[GCC 8.2.0]
python-bits: 64
OS: Linux
OS-release: 4.15.0-74-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8
libhdf5: 1.10.2
libnetcdf: 4.4.1.1

xarray: 0.14.1
pandas: 0.25.3
numpy: 1.18.1
scipy: 1.2.0
netCDF4: 1.4.2
pydap: None
h5netcdf: None
h5py: None
Nio: None
zarr: None
cftime: 1.0.3.4
nc_time_axis: None
PseudoNetCDF: None
rasterio: None
cfgrib: None
iris: None
bottleneck: None
dask: 2.9.2
distributed: None
matplotlib: 3.1.2
cartopy: 0.17.0
seaborn: 0.9.0
numbagg: None
setuptools: 40.6.3
pip: 20.0.1
conda: None
pytest: None
IPython: 7.2.0
sphinx: None
</details>

#### Output of ``xr.show_versions()`` in the setup that was working
<details>
INSTALLED VERSIONS
------------------
commit: None
python: 3.5.2.final.0
python-bits: 64
OS: Linux
OS-release: 4.4.0-169-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

xarray: 0.10.7
pandas: 0.22.0
numpy: 1.14.2
scipy: 1.0.0
netCDF4: 1.3.1
h5netcdf: None
h5py: 2.6.0
Nio: None
zarr: None
bottleneck: None
cyordereddict: None
dask: 1.1.3
distributed: None
matplotlib: 2.2.0
cartopy: 0.16.0
seaborn: 0.8.1
setuptools: 26.1.1
pip: 19.3.1
conda: None
pytest: None
IPython: 6.2.1
</details>
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/3722/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue
564033048,MDExOlB1bGxSZXF1ZXN0Mzc0MzM1Mzc0,3766,Allow plotting bool data,5948670,closed,0,,,0,2020-02-12T14:22:11Z,2020-04-03T23:19:23Z,2020-04-03T23:19:23Z,CONTRIBUTOR,,0,pydata/xarray/pulls/3766,"as @dcherian said:

> matplotlib can plot `bool` values so we should add that to the check in `_ensure_plottable`.

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

 - [x] Closes #3722 

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