ENH: Tweaks to axis handling (esp for flex methods)

[jtratner]

• Add 'rows' as synonym for 'index' for DataFrame and Series - ENH: Make 'rows' an axis alias for 'index' #5309
• Allow Series to accept axis kwarg for flex ops (and only allow axis=0) - CLN: Add axis kwarg to Series wrapper for compat #5352
• Fix Panel functions that aren't getting axis correctly - BUG/ENH: Allow drop to accept axis name #5354

I think (2) may already be there, but I'm not sure and I want to check that.

This should be really trivial to do but it should make interactive playing around with frame and series a bit more intuitive. Don't think it makes sense for panel.

[jreback]

for 1) I think u can add it to the aliases map in core/generic (like major for major_axis in panel) and I think it will just work

[jtratner]

Yep that's exactly what I was thinking.

[TomAugspurger]

Would this be the correct place to handle synonyms for Panel axes as well? I've hit some methods that require axis to be an int instead of "items"/"major"/"minor". Panel.drop (which looks like its from generic) for example.

[jtratner]

@TomAugspurger Can you list all the functions where you find that (pref with an example, even if it's just calls on one function)? (I also recall hitting a few that were doing that). That's probably because the function is getting the axis in the wrong way (i.e., it needs to use _get_axis rather than doing something like self.axes[axis], etc).

Panel functions should end up with 'items' for 0, 'major_axis' or 'major' for 1, 'minor_axis' or 'minor' for 2.

Panel._setup_axes(axes=['items', 'major_axis', 'minor_axis'],
                  info_axis=0,
                  stat_axis=1,
                  aliases={'major': 'major_axis',
                           'minor': 'minor_axis'},
                  slicers={'major_axis': 'index',
                           'minor_axis': 'columns'})

[jreback]

@TomAugspurger you can add to #5044, we'll make a top-level checklist for these kinds of things

[jreback]

@jtratner whatever else you want to put in 0.13 ok....pls bump otherwise