Checking number of elements in Python's `Counter`

问题

Python 2.7/3.1 introduced the awesome collections.Counter.

My question: How do I count how many "element appearances" a counter has?

I want this:

len(list(counter.elements()))

But shorter.

回答1:

sum(counter.itervalues())

来源：https://stackoverflow.com/questions/5506359/checking-number-of-elements-in-pythons-counter