BUG: enabling subplots works unexpectedly

[sinhrks]

Found 2 minor issues related to plotting with subplots=True.

1. If DataFrame only has single column, plot raises TypeError. It is because _subplots returns Axes instance, not array.
2. If kind=scatter or kind=hexbin is specified with subplots=True, additional blank axes is drawn.

[sinhrks]

I found 3rd minor issue and fixed:

• Calling Series.plot with subplots=True raises AttributeError

[jreback]

seems reasonable, @TomAugspurger can you validate?

[TomAugspurger]

This is good. @sinhrks do you want this one merged before your #6656?

[sinhrks]

Yes, please. Later, I'll finish #6656.

[TomAugspurger]

@jreback this is OK, just a conflict in release.rst

Can I merge this from the command line with

git checkout -b sinhrks-scattersp2 master
git pull git://github.com/sinhrks/pandas.git scattersp2

fixing the conflict in release.rst, rebasing onto master, checking out master and merging this PR in, and pushing to upstream/master? I shouldn't force push to master right?

[jreback]

correct, don't force push to master

exactly correct on your git-fu!

[TomAugspurger]

OK thanks.

merged via 97c4a2e

Thank @sinhrks

[jorisvandenbossche]

@TomAugspurger maybe add this to the dev wiki somewhere? (how to merge a PR this way)

[TomAugspurger]

https://github.com/pydata/pandas/wiki/Merging-Commits started there.

[jreback]

nice!