max value of a list (of string items)

Question

Heroes =['Superman','Batman','Dudley Do-Right','Luke Skywalker']
max(Heroes)
'Superman'

Can someone please explain why the above result is 'Superman' not 'Dudley Do-Right'?

len(Heroes[0]) is 8

len(Heroes[2]) is 15

I'm confused.

Answer 1

Strings are compared by lexicographical ordering, not by length. S comes after D in the alphabet:

>>> 'Superman' > 'Dudley Do-Right'
True

An inefficient way to replicate what max() does, would be to sort the input sequence and pick the last value for the result. So [20, 10, 8, 15], when sorted, puts 20 last and that's what max() returns. Sorting the strings in Heroes results in Superman being listed last.

If you wanted to find the longest string, use the key argument to max():

max(Heroes, key=len)

Here, instead of comparing values in Heroes directly, max() compares the values by the return value of the key argument; now the value for which len() returns the largest value is returned as the maximum.

Demo:

>>> Heroes = ['Superman', 'Batman', 'Dudley Do-Right', 'Luke Skywalker']
>>> max(Heroes, key=len)
'Dudley Do-Right'