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.
1 Answer
A more efficient solution is to sum up the counts (values) of each element:
sum(counter.values())
In Python 3.x, values() returns a view object of the dict's values.
In Python 2.x, values() returned an actual list. To avoid creating a new list with Python 2.x, use itervalues() instead:
sum(counter.itervalues())
7 Comments
Sven Marnach
No, there is none.
Counter does not keep track of this information. At least summing the counts is much more efficient than len(list(counter.elements())).
Ram Rachum
This is (a) more efficient and (b) more succinct than my original method, but it's still ugly. If there's no better way, I suggest that there should be a
Counter.elements_count() method.Sven Marnach
@cool-RR: Just derive from
Counter and add that method. Making it O(1) is cumbersome though -- you would basically need to rewrite the whole Counter class.Ram Rachum
I think Python-ideas is the way to go.
Sven Marnach
@cool-RR: Well, I was assuming you just want to get the job done :)
|
Counter.elements_count()method might be added. Python issue: bugs.python.org/issue11733