Occurence

[Adem]

For counting hashable objects there is built-in collections.Counter.

This enables counting and representing results in different ways:

>>> from collections import Counter
>>> nums = [1, 2, 3, 1, 2, 5, 6, 7, 7]
>>> counts = Counter(nums)
>>> counts
Counter({1: 2, 2: 2, 7: 2, 3: 1, 5: 1, 6: 1})

Print out counted items with their occurrance (sorted):

>>> print(*(f'{num}:{count}' for num, count in counts.most_common()), sep='\n')
1:2
2:2
7:2
3:1
5:1
6:1

How many values were counted:

>>> sum(counts.values())
9

How many different objects were counted:

>>> len(counts)
6

All values in sorted order:

>>> print(*counts.elements())
1 1 2 2 3 5 6 7 7
>>> list(counts.elements())
[1, 1, 2, 2, 3, 5, 6, 7, 7]

It doesn't throw an error if asked for object (key) not present, it just 'nicely' says that count is zero:

>>> counts[1]
2
>>> counts[100]
0