finding max in python as per some custom criterion

Question

I can do max(s) to find the max of a sequence. But suppose I want to compute max according to my own function , something like so -

currmax = 0
def mymax(s)          


        

Answer 1

max(s, key=operator.methodcaller('arity'))

or

max(s, key=lambda x: x.arity())

Answer 2

You can still use the max function:

max_arity = max(s, key=lambda i: i.arity())

Answer 3

I think the generator expression of doublep is better, but we seldom get to use methodcaller, so...

from operator import methodcaller
max(map(methodcaller('arity'), s))

Answer 4

For instance,

max (i.arity() for i in s)