sel with method 'nearest' fails with AssertionError

The following fails

def test_sel_nearest():
    """Test `sel` with method='nearest'"""
    # create test data
    times = pd.date_range('2000-01-01', periods=4)
    foo = xr.DataArray([1,2,3,4], coords=dict(time=times), dims='time')
    
    # works
    expected = foo.sel(time='2000-01-01')
    
    # fails
    assert foo.sel(time='2000-01-01', method='nearest') == expected

with an AssertionError in xarray/core/variable.py:

C:\Users\uuu\AppData\Local\Continuum\Miniconda2\lib\site-packages\xarray\core\dataarray.pyc in sel(self, method, tolerance, **indexers)
    623             self, indexers, method=method, tolerance=tolerance
    624         )
--> 625         return self.isel(**pos_indexers)._replace_indexes(new_indexes)
    626 
    627     def isel_points(self, dim='points', **indexers):

C:\Users\uuu\AppData\Local\Continuum\Miniconda2\lib\site-packages\xarray\core\dataarray.pyc in isel(self, **indexers)
    608         DataArray.sel
    609         """
--> 610         ds = self._to_temp_dataset().isel(**indexers)
    611         return self._from_temp_dataset(ds)
    612 

C:\Users\uuu\AppData\Local\Continuum\Miniconda2\lib\site-packages\xarray\core\dataset.pyc in isel(self, **indexers)
    910         for name, var in iteritems(self._variables):
    911             var_indexers = dict((k, v) for k, v in indexers if k in var.dims)
--> 912             variables[name] = var.isel(**var_indexers)
    913         return self._replace_vars_and_dims(variables)
    914 

C:\Users\uuu\AppData\Local\Continuum\Miniconda2\lib\site-packages\xarray\core\variable.pyc in isel(self, **indexers)
    539             if dim in indexers:
    540                 key[i] = indexers[dim]
--> 541         return self[tuple(key)]
    542 
    543     def _shift_one_dim(self, dim, count):

C:\Users\uuu\AppData\Local\Continuum\Miniconda2\lib\site-packages\xarray\core\variable.pyc in __getitem__(self, key)
    377         # orthogonal indexing should ensure the dimensionality is consistent
    378         if hasattr(values, 'ndim'):
--> 379             assert values.ndim == len(dims), (values.ndim, len(dims))
    380         else:
    381             assert len(dims) == 0, len(dims)

AssertionError: (0, 1)

It does not matter which type the dimension has that is indexed:

def test_sel_nearest_int():
    """Test `sel` with method='nearest'"""
    bar = xr.DataArray([1, 2, 3, 4], coords=dict(dummy=range(4)), dims='dummy')
    
    # works
    expected = bar.sel(dummy=3)
    
    # fails
    assert bar.sel(dummy=3, method='nearest') == expected

This is on Miniconda for Windows 64 bit with conda-forge and IOOS builds and

• xarray=0.8.2
• pandas=0.19.1
• numpy=1.11.2

Why might this be? Am I doing something wrong?

[shoyer]

Sounds like we need to add 64-bit Python 2.7 on Windows to our build matrix!

And also a more robust check for integer types in variable.py.

[joschkazj]

At our institute we use Python (both v2.7 and 3.x) exclusively on x64 systems to make use of the entire memory on our workstations. Since all relevant (binary) scientific packages are released as 64-bit versions, 32 bit Python is obsolete for our use cases.

Just for reference (I don’t develop on Windows), do we need to test both 32 and 64 bit Windows installs?

As some binary dependencies are involved, both have to be tested.