Sum of all counts in a collections.Counter

python python-3.x counter
Baz picture Baz · Sep 3, 2013 · Viewed 40.9k times · Source

What is the best way of establishing the sum of all counts in a collections.Counter object?

I've tried:

sum(Counter([1,2,3,4,5,1,2,1,6]))

but this gives 21 instead of 9?

Answer

NPE picture NPE · Sep 3, 2013

The code you have adds up the keys (i.e. the unique values in the list: 1+2+3+4+5+6=21).

To add up the counts, use:

In [4]: sum(Counter([1,2,3,4,5,1,2,1,6]).values())
Out[4]: 9

This idiom is mentioned in the documentation, under "Common patterns".

Related questions

Creating an Ordered Counter

I've been reading into how super() works. I came across this recipe that demonstrates how to create an Ordered Counter: from collections import Counter, OrderedDict class OrderedCounter(Counter, OrderedDict): 'Counter that remembers the order elements are first seen' def __repr__(…

Read More
Convert bytes to a string

I'm using this code to get standard output from an external program: >>> from subprocess import * >>> command_stdout = Popen(['ls', '-l'], stdout=PIPE).communicate()[0] The communicate() method returns an array of bytes: >>> …

Read More
Best way to convert string to bytes in Python 3?

There appear to be two different ways to convert a string to bytes, as seen in the answers to TypeError: 'str' does not support the buffer interface Which of these methods would be better or more Pythonic? Or is it …

Read More