counting element occurrences in nested lists

Question

This is probably quite a straightforward question, but I can\'t find an answer elsewhere so I\'ll ask. What is the best way to find the number of times an element appears in

Answer 1

from collections import Counter
from itertools import chain

counts = Counter(chain.from_iterable(my_list))

or generate a new list and use count:

new_list = list(chain.from_iterable(my_list))
print new_list.count(whatever)

If you wanted how many times 'a' is the first, then something like:

sum(1 for el in my_list if el[0] is a) # or == a if object identity is not required