OWRank: sort NaNs last; fix sort indicator

[kernc]

Issue

Fixes #2617

Description of changes

Always sort NaNs last. Implemented by exposing reimplementable AbstractSortTableModel._argsortData(). Also fix header indicator by sorting via view.horizontalHeader().setSortIdicator() instead of its model.

Includes

• Code changes
• Tests
• Documentation

[codecov-io]

Codecov Report

Merging #2618 into master will increase coverage by <.01%.
The diff coverage is 94.73%.

@@            Coverage Diff            @@
##           master   #2618      +/-   ##
=========================================
+ Coverage   74.99%     75%   +<.01%     
=========================================
  Files         331     331              
  Lines       58076   58104      +28     
=========================================
+ Hits        43555   43581      +26     
- Misses      14521   14523       +2

[ajdapretnar]

This looks good.

Would you care to check this error, too?

orange/orange3/Orange/widgets/settings.py:380: UserWarning: Could not read defaults for widget <class 'Orange.widgets.data.owrank.OWRank'>
The following error occurred:

'headerState'
.format(self.widget_class, ex))

[ajdapretnar]

Still some comments.

1. When I sort by, say, Info. gain and chance the data set, the sorting doesn't pertain. I have to re-sort again even though there's an arrow indicating the sorted column.
2. Could we turn off sorting by # or is this not possible with the model?

[kernc]

Fixed.

Could we turn off sorting by # or is this not possible with the model?

Sure it's possible. But one may wish to split scores by variable type, or to keep discrete variables with the number of values within a certain threshold. My vote is against.

[ajdapretnar]

But one may wish to split scores by variable type, or to keep discrete variables with the number of values within a certain threshold. My vote is against.

Ok. It is just a little ugly when sorting by #. Perhaps add a tad of extra width then?

[kernc]

@ajdapretnar Wide enough?

[ajdapretnar]

Yes, but now it looks annoyingly wide. 😆 I'm such a brat. I'll merge this as it is a great solution! 👌

[ajdapretnar]

Ok, I said I would merge this, but codecov is complaining...