Remove attribute-style accesses to (Geo)DataFrames columns and xarray Datasets variables and attributes

[luseverin]

Changes proposed in this PR:

• Removal of attribute style-accesses to columns of pandas DataFrames, GeoDataFrames, and variables and attributes of xarray DataSets and DataArray.
• Mention this policy in the climada convention guide

This PR fixes SCRUM userstory 100: Avoid attribute-style access to DataFrame columns (https://tree.taiga.io/project/emanuel-schmid-climada/us/100).

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[luseverin]

I did my best to replace all instances of attribute-style accesses with the recommended keyword-style accesses. Please let me know if you spot some instances that I missed!

What I still need to do is to update tests (as I assume this needs to be done as well).

[chahank]

What is the goal of this class?

[luseverin]

Sorry, it got mistakenly commited, I will remove it. It was a script to try to automatically find out occurences of attribute-style accesses but it was not working out well..

[spjuhel]

Great job!

I looked around with different regexps based on yours:

• There are some "exp.gdf.value" in util/lines_polys_handler.py (in docstrings mainly)
• entity/measure/base.py:492
• engine/unsequa/unc_output.py:1028

I did not find others (except for tests, but you said you still haven't done these yet)

[luseverin]

Ok so I removed the few instances that I missed + the ones in the tests. Everything should be covered now. However I now have some tests failing with some weird errors e.g. AttributeError: module 'importlib_metadata' has no attribute 'entry_points' . I am not sure how this relates to my changes. When I did the make unit_test and make integ_test everything was passing.. Any idea where this might come from?

[spjuhel]

Very good job! You can merge as soon as we understand why the test are failing on Jenkins.

@emanuel-schmid any idea?

[emanuel-schmid]

awesome! many thanks!

(the importlib_metadata error was most likely just about some incompatible conda package)