Add string arguments for Cube methods

[gcaria]

🚀 Pull Request

Description

Resolves #3602

I have just started to work on this, and after adding a short test I get 5 failures when testing lib/iris/tests/unit/cube/test_Cube.py, all AssertionErrors similar to:

AssertionError: CML do not match: /home/gcaria/github/iris/lib/iris/tests/results/unit/cube/Cube/xml/checksum_ignores_masked_values.cml

which don't seem to be related to the test I've added. I've followed the instructions for running the tests so I'm not sure what I'm missing.

[rcomer]

Hi @gcaria, thanks for the contribution! I’m not sure about that specific error, but I can see that your branch is a couple of commits behind the master branch. The most recent commit to master incorporates a switch from Travis-CI to Cirrus-CI to run the tests within the PR. So I suggest rebasing to pick up that change, and then we can see your test output here. So something like:

git fetch upstream
git rebase upstream/master
git push -f origin

[rcomer]

Depending how and exactly when you created your python environment, it may be also be worth worth re-doing that. cftime v1.3 was recently released, and caused all sorts of failures within Iris. We’ve temporarily pinned the cftime version (#3927), but that was also after you created your branch.

So if you rebase, then create a new environment from the source, then run the tests again, you might get a different result.

[gcaria]

Thanks @rcomer for the useful feedback !

In addition to changing the cftime version, I've also switched to python3.7 (was using 3.8 before) which was surely part of the problem, at least locally. Now everything works :)

I see that in #3295 the docstring for the remove_cell_measure was also expanded.
Would it be appropriate to have the same also for the modified methods of this PR ?

[rcomer]

Hi @gcaria, glad you got the tests working! I don't think I'm the best person to advise on this specific change as I haven't done anything with this part of the code. Looks like @stephenworsley has done a lot in this area so hopefully he can advise.

[bjlittle]

@gcaria Awesome contribution! Thanks for taking the time to push this fix to iris. Much appreciated 😄

Could I ask you to also make a whatsnew entry to accompany this pull-request?

Simply make the following addition to the <root-dir>/docs/iris/src/whatsnew/latest.rst file, under the section "🐛 Bugs Fixed", with something along the lines of:

* `@gcaria`_ fixed :meth:`~iris.cube.Cube.cell_measure_dims` to also accept the string name of a :class:`~iris.coords.CellMeasure`. (:pull:`3931`)
* `@gcaria`_ fixed :meth:`~iris.cube.Cube.ancillary_variable_dims` to also accept the string name of a :class:`~iris.coords.AncillaryVariable`. (:pull:`3931`)

Also, at the end of the latest.rst file add the following entry:

.. _@gcaria: https://github.com/gcaria

Then we'll be good to go! 👍

[gcaria]

Oh I see this was all documented here, my bad for missing it and thanks for pointing that out!

[bjlittle]

@gcaria Perfect, thanks 👍