9.3 Indexing with .str

You can use [] notation to directly index by position locations. If you index past the end of the string, the result will be a NaN.

In [1]: s = pd.Series(['A', 'B', 'C', 'Aaba', 'Baca', np.nan,
   ...:                'CABA', 'dog', 'cat'])
   ...: 

In [2]: s.str[0]
Out[2]: 
0      A
1      B
2      C
3      A
    ... 
5    NaN
6      C
7      d
8      c
dtype: object

In [3]: s.str[1]
Out[3]: 
0    NaN
1    NaN
2    NaN
3      a
    ... 
5    NaN
6      A
7      o
8      a
dtype: object