Inconsistent Series subsetting behaviour

[gerigk]

Series in 0.7 RC1 have some weird behaviour when selecting by index.

y
a 0
0 1
1 2
Name: a
y[0]
1 # expected
y[[0,1]]
a 0 # wrong?
0 1
Name: a
y[[1,2]]
0 1
1 2
Name: a
y.ix[[0,1]] # this also doesnt work
a 0
0 1
Name: a

[wesm]

This actually is the behavior I would expect and you've identified a pathological ambiguous case where it's very hard for the code to know what's the right thing to do. ix uses location-based indexing whenever a sequence of integers is passed as long as the index is not integers. But in this case of course:

In [1]: s = Series([0, 1, 2], index=['a', 0, 1])

In [2]: s
Out[2]: 
a    0
0    1
1    2

In [3]: s.index.inferred_type
Out[3]: 'mixed'

You can force exact label-indexing using the reindex function. That is actually the best way to guarantee exact label-based indexing:

In [4]: s.reindex([0, 1])
Out[4]: 
0    1
1    2