"IndexingError: Unalignable boolean Series key provided" when passing an empty object Series

[sadruddin]

For some reason, with 0.13, an empty object Series is interpreted as a boolean one, when using to fetch elements in another Series:

pandas.Series(['A', 'B'])[pandas.Series([], dtype=object)]

The following works though, so the dtype confusion seems to be confined to empty Series:

pandas.Series(['A', 'B'])[pandas.Series(['C'], dtype=object)]

[jreback]

hmm...

the 2nd acts like a reindex, while the 1st is odd as well

marking as a bug/api issue...

what do you think they should do?

[sadruddin]

Why do you think that the 2nd is odd? Isn't it what one would expect when passing a Series, i.e. something equivalent to passing an array (using the Series' values)?
I would expect the 1st to return the same thing as what happens when passing a Series of dtype float, i.e. an empty Series. N.B: This used to work in 0.12

[jreback]

@sadruddin see #5880
should close this

The handling of a bool dtyped indexer that is empty would raise in 0.12. I changed it to work in 0.13, but could go either way. thoughts? (its the 3rd one down)

[sadruddin]

In my opinion, given bool's special case, any non-matching length bool dtyped pandas.Series, including with length 0, should raise an exception. So 0.12 behaviour seems logical to me.

[jreback]

agreed....reverting back to that behavior..

[jreback]

@sadruddin thanks for the report!