Pythonic custom sort for letter grades 'D', 'C-' ,…, 'A+'?

Question

Is there a more Pythonic, compact, intuitive way to sort letter-grades than this (without using a custom dict)?

grades = [\'B-\',\'C\',\'B\',\'C+\',\'A\',\'D+\',         


        

Answer 1

Yes-ish?

>>> sorted(grades, key=lambda g: g + ',')
['A+', 'A', 'A-', 'B+', 'B', 'B-', 'C+', 'C', 'C-', 'D+', 'D']

Clearly more compact, and I'd say also pythonic, just not very intuitive :-P

Works because '+' < ',' < '-'.

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Another one:

>>> sorted(grades, key=lambda g: (g[0], ' -'.find(g[1:])))
['A+', 'A', 'A-', 'B+', 'B', 'B-', 'C+', 'C', 'C-', 'D+', 'D']

Suffix + won't be found in ' -', so find returns -1. Empty suffix results in 0, and suffix - results in 1.