Concat single series along columns returns a DataFrame

[TomAugspurger]

This came up in dask, I wanted to confirm whether or not it's intentional before dask mirrors pandas:

In [6]: import pandas as pd

In [7]: pd.concat([pd.Series([1, 2], name='foo')], axis='columns')
Out[7]:
   foo
0    1
1    2

In [8]: type(_)
Out[8]: pandas.core.frame.DataFrame

I think it's fine for concat(..., axis=1) to always return a DataFrame, but we should document that.

[jreback]

I wouldn't except this to do anything else. if you want to add some docs go for it. this is long estallished behavior.

[jorisvandenbossche]

I agree, I think this is the sensible thing to do.