Using .loc to retrieve from a Python Pandas series is more convenient. But .iloc is faster:
s = pd.Series([10, 20, 30], index=list('abc'))%timeit s.loc[‘a’] # 2.09 μs
%timeit s.iloc[0] # 1.5 μs
%timeit s.loc[[‘a’, ‘b’]] # 105 μs
%timeit s.iloc[[0, 1]] # 26.4 μs