How do I count occurrence of unique values inside a list [duplicate]

In addition, use collections.Counter to refactor your code:

from collections import Counter

words = ['a', 'b', 'c', 'a']

Counter(words).keys() # equals to list(set(words))
Counter(words).values() # counts the elements' frequency

Output:

['a', 'c', 'b']
[2, 1, 1]