How to find most common element in a list of list?

Question

I understand

a = max(set(lst), key=lst.count)

will derive most common element in a list

but how do you derive most common element

Answer 1

You have to flattern your list (with chain(*lst)), then count entry of each element of your list with Counter(chain(*lst).most_common()) and sort the result.

from itertools import chain
from collections import Counter

lst = [['1','2','3','4'],['1','1','1','1'],['1','2','3','4']]
sorted(Counter(chain(*lst)).most_common())[0][0]