一、Counter (主要用來做統計)
from collections import Counter
c = Counter('abcdeabcdabcaba')
print c.most_common(3)
# [('a', 5), ('b', 4), ('c', 3)]
print sorted(c.elements())
# ['a', 'a', 'a', 'a', 'a', 'b', 'b', 'b', 'b', 'c', 'c', 'c', 'd', 'd', 'e']
二、defaultdict
from collections import defaultdict
def a():
return [1,2,3]
dd = defaultdict(a, a='b')
print dd['a']
print dd['b']
三、OrderedDict
d = OrderedDict()
d['a'] = 'A'
d['b'] = 'B'
d['c'] = 'C'
for k, v in d.items():
print k, v
四、deque
from collections import deque
# 雙端序列,和列表操作差不多。詳見collections模塊
q = deque('12345')
print q
# deque(['1', '2', '3', '4', '5'])