How to get unique values with respective occurrence count from a list in Python?

Question

I have a list which has repeating items and I want a list of the unique items with their frequency.

For example, I have [\'a\', \'a\', \'b\', \'b\', \'b\']

Answer 1

I know this isn't a one-liner... but to me I like it because it's clear to me that we pass over the initial list of values once (instead of calling count on it):

>>> from collections import defaultdict
>>> l = ['a', 'a', 'b', 'b', 'b']
>>> d = defaultdict(int)
>>> for i in l:
...  d[i] += 1
... 
>>> d
defaultdict(, {'a': 2, 'b': 3})
>>> list(d.iteritems())
[('a', 2), ('b', 3)]
>>>