Sum of all counts in a collections.Counter

Question

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?

It gives you the sum of the unique keys. – Tomasz Gandor Nov 16 '18 at 10:43 — Tomasz Gandor, Nov 16 '18 at 10:43

NPE · Accepted Answer · 2013-09-03T13:31:06.403

87

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".

edited Sep 03 '13 at 13:31

answered Sep 03 '13 at 13:25

NPE

...btw, this is always going to be equal to len([1,2,3,4,5,1,2,1,6]), so it use that method only when you just have the counter... – ntg Mar 21 '22 at 10:35

score 26 · Answer 2 · answered Sep 03 '13 at 13:25

26

Sum the values:

sum(some_counter.values())

Demo:

>>> from collections import Counter
>>> c = Counter([1,2,3,4,5,1,2,1,6])
>>> sum(c.values())
9

answered Sep 03 '13 at 13:25

Martijn Pieters

Xavier Guihot · Answer 3 · 2021-10-06T09:31:59.560

25

Starting in Python 3.10, Counter is given a total() function which provides the sum of the counts:

from collections import Counter

Counter([1,2,3,4,5,1,2,1,6]).total()
# 9

edited Oct 06 '21 at 09:31

answered May 13 '21 at 16:41

Xavier Guihot

score 3 · Answer 4 · answered Sep 03 '13 at 13:27

3

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

answered Sep 03 '13 at 13:27

martyn

4 Answers4