python - Length of longest word in a list

Question

What is the more pythonic way of getting the length of the longest word:

len(max(words, key=len))

Or:

max(len(w) for w in words)

Or.. something else? words is a list of strings. I am finding I need to do this often and after timing with a few different sample sizes the first way seems to be consistently faster, despite seeming less efficient at face value (the redundancy of len being called twice seems not to matter - does more happen in C code in this form?).

Answer 1

Although:

max(len(w) for w in words)

does kind of "read" easier - you've got the overhead of a generator.

While:

len(max(words, key=len))

can optimise away with the key using builtins and since len is normally a very efficient op for strings, is going to be faster...