ENH: resample methods with tolerance

[observingClouds]

• ENH: resample methods bfill, pad, nearest accept tolerance keyword

• Closes Resample with limit/tolerance #2695
• Tests added
• Fully documented, including whats-new.rst for all changes and api.rst for new API

[jhamman]

Thanks @observingClouds - At first glance, this seems right but we'll want some tests to confirm. You'll probably want to put these in test_missing.py. That's where the existing tests for bfill/pad/etc are so should be easy to extend for this feature.

[observingClouds]

Sure @jhamman, I'll add some tests.
However, I thought the test should rather go into test_dataarray.py than test_missing.py, because
this is an improvement to resample/_upsample?

Something like

    def test_upsample_tolerance(self):
        # Test tolerance keyword for upsample methods bfill, pad, nearest
        times = pd.date_range('2000-01-01', freq='1D', periods=2)
        times_upsampled = pd.date_range('2000-01-01', freq='6H', periods=5)
        array = DataArray(np.arange(2), [('time', times)])

        # Forward fill
        actual = array.resample(time='6H').ffill(tolerance='12H')
        expected = DataArray([0., 0., 0., np.nan, 1.],
                             [('time', times_upsampled)])
        assert_identical(expected, actual)

[jhamman]

@observingClouds - I had forgotten the upsample tests were in test_dataarray.py. That seems like a better place to test this functionality.

[pep8speaks]

Hello @observingClouds! Thanks for updating the PR.

Cheers ! There are no PEP8 issues in this Pull Request. 🍻

Comment last updated on January 30, 2019 at 22:33 Hours UTC

[shoyer]

Two minor suggestions on the test, but other this looks good to me!

[dcherian]

Thanks @observingClouds

[dcherian]

Mention that "tolerance" is in coordinate (or label) units, not index units and that the index version is limit

[observingClouds]

The unit for tolerance is now (a878ebc) explicitly mentioned in the time-series example. However, I did not comment on the index method as this has not been implemented for the resample method, yet. The index method seems to be a bigger/other project.

[shoyer]

Thanks @observingClouds -- really nice PR!