v = (2,3)

 from collections import namedtuple
 Vector = namedtuple('Vector', ['x', 'y'])
 v = Vector(2,3)

 type(v)
<class '__main__.Vector'>
 isinstance(v, Vector)
True
 isinstance(v, tuple)

 Circle = namedtuple('Circle', ['x', 'y', 'r'])
# namedtuple('名稱(chēng)', [‘屬性列表'])

 from collections import deque
 deq = deque([1, 2, 3])
 deq.append(4)
 deque([1, 2, 3, 4])
 deq.appendleft(5)
deque([5, 1, 2, 3, 4])
 deq.pop()
 deq.popleft()
deque([1, 2, 3])

 from collections import defaultdict?? ??? ?
 dd = defaultdict(lambda: 'defaultvalue')
 dd['key1'] = 'a'
 dd['key1']
'a'
 dd['key2'] # key2未定義，返回默認(rèn)值
'defaultvalue'

 from collections import OrderedDict
 d = dict([('a', 1), ('b', 2), ('c', 3)])
 d # dict的Key是無(wú)序的
{'a': 1, 'c': 3, 'b': 2}
 od = OrderedDict([('a', 1), ('b', 2), ('c', 3)])
 od # OrderedDict的Key是有序的
OrderedDict([('a', 1), ('b', 2), ('c', 3)])
#注意，OrderedDict的key會(huì)按照插入的順序排列，不是key本身排序
 od = OrderedDict()
 od['z'] = 1
 od['y'] = 2
 od['x'] = 3
 list(od.keys()) # 按照插入的Key的順序返回
['z', 'y', 'x']
#OrderedDict可以實(shí)現(xiàn)一個(gè)FIFO（先進(jìn)先出）的dict，當(dāng)容量超出限制時(shí)，先刪除最早添加的key。
from collections import OrderedDict
class LastUpdatedOrderedDict(OrderedDict):
    def __init__(self, capacity):
        super(LastUpdatedOrderedDict, self).__init__()
        self._capacity = capacity
    def __setitem__(self, key, value):
        containsKey = 1 if key in self else 0
        if len(self) - containsKey >= self._capacity:
            last = self.popitem(last=False)
            print('remove:', last)
        if containsKey:
            del self[key]
            print('set:', (key, value))
        else:
            print('add:', (key, value))
        OrderedDict.__setitem__(self, key, value)

from collections import ChainMap
import os, argparse
# 構(gòu)造缺省參數(shù):
defaults = {
    'color': 'red',
    'user': 'guest'
}
# 構(gòu)造命令行參數(shù):
parser = argparse.ArgumentParser()
parser.add_argument('-u', '--user')
parser.add_argument('-c', '--color')
namespace = parser.parse_args()
command_line_args = { k: v for k, v in vars(namespace).items() if v }
# 組合成ChainMap:
combined = ChainMap(command_line_args, os.environ, defaults)
# 打印參數(shù):
print('color=%s' % combined['color'])
print('user=%s' % combined['user'])

$ python3 use_chainmap.py 
color=red
user=guest

$ python3 use_chainmap.py -u bob
color=red
user=bob

$ user=admin color=green python3 use_chainmap.py -u bob
color=green
user=bob

from collections import Counter
 s = 'abbcccdddd'
 Counter(s)
Counter({'d': 4, 'c': 3, 'b': 2, 'a': 1})
#Counter實(shí)際上也是dict的一個(gè)子類(lèi)。