Fundamental issue with ix
Using square bracket indexing [x] on a Series where x is an integer 
seems to return: 
- the item at the index x if such index is present 
- the x-th item if the index does not exist 
  To be precise: 
  In [190]: ss = pandas.Series(range(10), index = range(0, 20, 2)) 
   ...: print ss 
   ...: 
  0     0 
  2     1 
  4     2 
  6     3 
  8     4 
  10    5 
  12    6 
  14    7 
  16    8 
  18    9 
  Name: None, Length: 10 
  In [191]: ss[0] 
  Out[191]: 0 
  In [192]: ss[1] 
  Out[192]: 1 
  In [193]: ss[2] 
  Out[193]: 1 
  In [194]: ss[3] 
  Out[194]: 3 
  In [195]: ss[4] 
  Out[195]: 2 
  In [196]: ss[17] 

---

KeyError                                  Traceback (most recent call 
last) 
/home/marius/Code/ccapital/<ipython-input-196-065c9192fad1> in 
<module>() 
----> 1 ss[17] 
/usr/lib64/python2.7/site-packages/pandas/core/series.pyc in 
**getitem**(self, key) 
    267                     except Exception, _: 
    268                         pass 
--> 269                     raise e1 
    270         except TypeError: 
    271             pass 
KeyError: 17 
In [197]: ss[18] 
Out[197]: 9 
# 

Is this behaviour intended? To me it seems like a fundamental bug. 

From the documentation: 
Select row by location (int):   df.ix[loc]      Series 
Which is not what ix seems to be doing. 

If the labels are made strings, the behaviour is utterly different 
(correct according to the documentation): 
ss = pandas.Series(range(10), index = map(str, range(0, 20, 2))) 
print ss 
0     0 
2     1 
4     2 
6     3 
8     4 
10    5 
12    6 
14    7 
16    8 
18    9 
Name: None, Length: 10 
ss[0] 
Out[220]: 0 
ss[1] 
Out[221]: 1 
ss[2] 
Out[222]: 2 

Many thanks,
    -- Marius 
