API: A tuple passed to DataFame.sort_index will be interpreted as the levels of the index (GH4370)

[jreback]

closes #4370

In [3]: df = DataFrame({'one':[2,1,1,1],'two':[1,3,2,4],'three':[5,4,3,2]}) In [7]: df.columns = MultiIndex.from_tuples([('a','one'),('a','two'),('b','three')]) In [8]: df Out[8]: a b one two three 0 2 5 1 1 1 4 3 2 1 3 2 3 1 2 4 [4 rows x 3 columns] 

These are now equivalent. Used to be able to do only the 2nd.

In [9]: df.sort_index(by=('a','two')) Out[9]: a b one two three 3 1 2 4 2 1 3 2 1 1 4 3 0 2 5 1 [4 rows x 3 columns] In [10]: df.sort_index(by=[('a','two')]) Out[10]: a b one two three 3 1 2 4 2 1 3 2 1 1 4 3 0 2 5 1 [4 rows x 3 columns] 

[jreback]

anyone think this is a bad idea?

[jorisvandenbossche]

Looks like a good idea at first sight. Should this also be implemented for sort?

[jreback]

Dataframe.sort just passed thru to sort_index...but'll change the doc-string