python 内置模块collectio

1、namedtuple

from collections import namedtuple

websites = [ ('Sohu', 'http://www.google.com/', u'张朝阳'), ('Sina', 'http://www.sina.com.cn/', u'王志东'), ('163', 'http://www.163.com/', u'丁磊') ]

Website = namedtuple('Website', ['name', 'url', 'founder']) mywebsite = Website('ading', 'http://blog.65535.fun', u'林天来') print(mywebsite.name) print(mywebsite.url) print(mywebsite.founder) for website in websites: website = Website._make(website) print website

2、deque In [1]: from collections import deque

In [2]: mydeque = deque(maxlen=10)

In [3]: mydeque.maxlen Out[3]: 10

In [4]: mydeque.append(1)

In [5]: mydeque.append(10)

In [6]: mydeque Out[6]: deque([1, 10])

In [7]: mydeque.appendleft('a')

In [8]: mydeque.appendleft('b')

In [9]: mydeque Out[9]: deque(['b', 'a', 1, 10])

In [10]: mydeque.pop() Out[10]: 10

In [11]: mydeque Out[11]: deque(['b', 'a', 1])

In [12]: mydeque.popleft() Out[12]: 'b'

In [13]: mydeque Out[13]: deque(['a', 1])

deque 还有常用的方法 ：copy,reverse, insert, clear

3、OrderedDict 使用dict时，在遍历字典时是无法指定key的顺序的，但OrderedDict 是可以的

In [1]: from collections import OrderedDict

In [2]: od = OrderedDict

In [3]: od = OrderedDict()

In [4]: od['aa'] = 11

In [5]: od['bb'] = 22

In [6]: od['cc'] = 33

In [7]: od Out[7]: OrderedDict([('aa', 11), ('bb', 22), ('cc', 33)])

4、defaultdict 默认值是在调用difaultdict 时传入一个可调用函数。 In [1]: from collections import defaultdict

In [2]: df = defaultdict(lambda: 'aa')

In [3]: df['key1'] = 11

In [4]: df['key2'] Out[4]: 'aa'

In [5]: df Out[5]: defaultdict(<function main.<lambda>()>, {'key1': 11, 'key2': 'aa'})