Series/DataFrame lookup values behave inconsistently

[yueatwork]

One feature about DataFrame that I found uncomfortable is the inconsistency of results:

x = pd.DataFrame({'A': [1,2,3,4,5]}, index=['a','b','c','d','e'])
x.loc[['a', 'f']]  # fine, value of 'f' is numpy.nan
x.loc[['f']]  # throws 

When developing data applications, I spend lot of time fixing this issue. I think we should make it more consistent. Either always returns (preferred) or always throws.

[jreback]

duplicate of #10695

lots of discussion there.

[jreback]

this has nothing to do with Series/DataFrame, they both work the same. rather whether a single missing label raises, while a list that includes at least one label will be like a .reindex

[yueatwork]

Thank you. Seems this isn't an easy fix. I will stick with the current framework until I figure out a better design.