collections.Counter

按ascii顺序排序

from collections import Counter

>>> c = Counter('hello,world')
Counter({'l': 3, 'o': 2, 'e': 1, 'd': 1, 'h': 1, ',': 1, 'r': 1, 'w': 1})
按频率排序
>>> c = Counter(numbers)
>>> c.most_common()
[('1', 8),
 ('2', 6),
 ('6', 6),
 ('5', 5),
 ('4', 5),
 ('7', 5),
 ('0', 3),
 ('9', 3),
 ('8', 2),
 ('3', 1)]