Fastest way to count number of occurrences in a Python list

Question

I have a Python list and I want to know what\'s the quickest way to count the number of occurrences of the item, \'1\' in this list. In my actual case, the item

Answer 1

Combination of lambda and map function can also do the job:

list_ = ['a', 'b', 'b', 'c']
sum(map(lambda x: x=="b", list_))
:2