BUG: Multijoining indexes always returns indexers, ignores function parameters · Issue #34074 · pandas-dev/pandas (original) (raw)

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of pandas.
• (optional) I have confirmed this bug exists on the master branch of pandas.

Code Sample

frame = pd.DataFrame([(1,2,3,4),(4,5,6,7)],columns=["i1", "i2", "i3","val"]).set_index(["i1","i2","i3"]) frame2 = pd.DataFrame([(1,2,3),(4,5,6)],columns=["i1", "i2", "val"]).set_index(["i1","i2"]) frame.index.join(frame2.index,return_indexers=False) (MultiIndex([(1, 2, 3), (4, 5, 6)], names=['i1', 'i2', 'i3']), None, None)

Problem description

Parameter return_indexers is ignored in some cases of __join_multi

Expected Output

frame.index.join(frame2.index,return_indexers=False) MultiIndex([(1, 2, 3), (4, 5, 6)], names=['i1', 'i2', 'i3'])