Test Failure: test_datetime_line_plot

[jhamman]

We're getting a single test failure in the plot tests on master (link to travis failure. I haven't been able to reproduce this locally yet so I'm just going to post here to see if anyone has any ideas.

Code Sample

___________________ TestDatetimePlot.test_datetime_line_plot ___________________
self = <xarray.tests.test_plot.TestDatetimePlot testMethod=test_datetime_line_plot>
    def test_datetime_line_plot(self):
        # test if line plot raises no Exception
>       self.darray.plot.line()
xarray/tests/test_plot.py:1333: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
xarray/plot/plot.py:328: in line
    return line(self._da, *args, **kwargs)
xarray/plot/plot.py:223: in line
    _ensure_plottable(x)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
args = (<xarray.DataArray 'time' (time: 12)>
array([datetime.datetime(2017, 1, 1, 0, 0),
       datetime.datetime(2017, 2, 1,... 12, 1, 0, 0)], dtype=object)
Coordinates:
  * time     (time) object 2017-01-01 2017-02-01 2017-03-01 2017-04-01 ...,)
numpy_types = [<class 'numpy.floating'>, <class 'numpy.integer'>, <class 'numpy.timedelta64'>, <class 'numpy.datetime64'>]
other_types = [<class 'datetime.datetime'>]
x = <xarray.DataArray 'time' (time: 12)>
array([datetime.datetime(2017, 1, 1, 0, 0),
       datetime.datetime(2017, 2, 1, ...7, 12, 1, 0, 0)], dtype=object)
Coordinates:
  * time     (time) object 2017-01-01 2017-02-01 2017-03-01 2017-04-01 ...
    def _ensure_plottable(*args):
        """
        Raise exception if there is anything in args that can't be plotted on an
        axis.
        """
        numpy_types = [np.floating, np.integer, np.timedelta64, np.datetime64]
        other_types = [datetime]
    
        for x in args:
            if not (_valid_numpy_subdtype(np.array(x), numpy_types)
                    or _valid_other_type(np.array(x), other_types)):
>               raise TypeError('Plotting requires coordinates to be numeric '
                                'or dates.')
E               TypeError: Plotting requires coordinates to be numeric or dates.
xarray/plot/plot.py:57: TypeError

Expected Output

This test was previously passing

Output of xr.show_versions()

https://travis-ci.org/pydata/xarray/jobs/326640013#L1262

[shoyer]

NumPy 1.14 just came out, it might be related to that.

[jhamman]

You're right. That's it. Do you know what the check for np.generic is trying to do here:

xarray/xarray/plot/plot.py

Lines 36 to 43 in ab0db05

	def _valid_other_type(x, types):
	"""
	Do all elements of x have a type from types?
	"""
	if not np.issubdtype(np.generic, x.dtype):
	return False
	else:
	return all(any(isinstance(el, t) for t in types) for el in np.ravel(x))

All the tests seem to pass with:

def _valid_other_type(x, types):
    """
    Do all elements of x have a type from types?
    """
    return all(any(isinstance(el, t) for t in types) for el in np.ravel(x))

[shoyer]

I think it was likely a work-around for some strange behavior in issubdtype -- likely exactly what was fixed on the numpy side by numpy/numpy#9505.