Python 3 Object-Oriented Programming - Third Edition

Counter

You'd think that you couldn't get much simpler than defaultdict(int), but the I want to count specific instances in an iterable use case is common enough that the Python developers created a specific class for it. The previous code that counts characters in a string can easily be calculated in a single line:

from collections import Counter 
def letter_frequency(sentence): 
    return Counter(sentence) 

The Counter object behaves like a beefed-up dictionary where the keys are the items being counted and the values are the quantities of such items. One of the most useful functions is the most_common() method. It returns a list of (key, count) tuples ordered by the count. You can optionally pass an integer argument into most_common() to request ...