Error accessing isnull() and notnull() on Dataset

[duncanwp]

Code Sample, a copy-pastable example if possible

# Create basic Dataset
import numpy as np
import pandas as pd
import xarray as xr

temp = 15 + 8 * np.random.randn(2, 2, 3)

precip = 10 * np.random.rand(2, 2, 3)
lon = [[-99.83, -99.32], [-99.79, -99.23]]
lat = [[42.25, 42.21], [42.63, 42.59]]

# for real use cases, its good practice to supply array attributes such as
# units, but we won't bother here for the sake of brevity
ds = xr.Dataset({'temperature': (['x', 'y', 'time'],  temp),
                 'precipitation': (['x', 'y', 'time'], precip)},
                coords={'lon': (['x', 'y'], lon),
                        'lat': (['x', 'y'], lat),
                        'time': pd.date_range('2014-09-06', periods=3),
                        'reference_time': pd.Timestamp('2014-09-05')})

# Both of these throw attribute errors
ds.notnull()
# ds.isnull()

Problem description

The above methods throw AttributeError: 'Variable' object has no attribute '_constructor' errors when called on Datasets. It's not clear if this operation is currently supported, but if it's not then it probably shouldn't be exposed through the API.

Expected Output

Dataset of boolean DataArrays indicating null-ness.

Output of xr.show_versions()

Show_versions() doesn't seem to exist in 0.9.6, but presumably this covers it:

Numpy version: 1.13.1
Pandas version: 0.21.0
XArray version: 0.9.6

[jhamman]

@duncanwp - can you try updating to the v0.10 release candidate. I think should fix this issue.

pip install --pre --upgrade --upgrade-strategy=only-if-needed xarray

[jhamman]

This is likely a duplicate of #1663, and was fixed by #1549.

[duncanwp]

Yes, you're right - it works now in 0.10.0rc1. Apologies for the noise!