collections

• 引入

  import collections

• Counter

  most_common

• In [6]: collections.Counter('abcdeabcdabcaba').most_common(3)

• Out[6]: [('a', 5), ('b', 4), ('c', 3)]

• 
  

• In [7]: collections.Counter('rommel').most_common(3)

• Out[7]: [('m', 2), ('e', 1), ('r', 1)]

• 
  

• In [8]: collections.Counter('rommel').most_common(1)

• Out[8]: [('m', 2)]

    update

In [10]: c1 = collections.Counter('aabc')

In [11]: c2 = collections.Counter('aac')

In [12]: c1

Out[12]: Counter({'a': 2, 'c': 1, 'b': 1})

In [13]: c2

Out[13]: Counter({'a': 2, 'c': 1})

In [14]: c1.update(c2)

In [15]: c1

Out[15]: Counter({'a': 4, 'c': 2, 'b': 1})

• OrderedDict

  有序字典

• In [19]: o1= collections.OrderedDict()

• 
  

• In [20]: o1['k1']=2

• 
  

• In [21]: o1['k2']=2

• 
  

• In [22]: o1

• Out[22]: OrderedDict([('k1', 2), ('k2', 2)])

    默認字典

• defaultdict(list)

• defaultdict(tuple)
  

感覺這個不太喜歡 可能是自己scala寫多了 感覺好廢物的樣子