Negative index in pandas give a KeyError unlike lists

Question

With Python lists you can slice with negative indices.

a = [1,2,3,4,5,6,7,8,9]
print(a[-1])

will print 9 as expected.

However,

a = pd.Series([1,2,3,4,5,6,7,8,9])
print(a[-1])

gives KeyError: -1L

Answer 1

Use iloc to get by position rather than label:

In [11]: a.iloc[-1]
Out[11]: 9

See selection section of the docs.