collection counter 类找出序列中出现次数最多的元素

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我是靠谱客的博主健壮汽车，最近开发中收集的这篇文章主要介绍collection counter 类找出序列中出现次数最多的元素，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

 
  ''' 
 
  找出序列中的出现次数最多的元素 
 
  运用  
 
  colections 中的counter类中的most_common()方法 
 
  底层：counter是一个字典 ，在元素和次数之间作了映射 
 
  ''' 
 
   lists = [ 
  'look', 
  'see', 
  'aaa', 
  'aaa', 
  'b', 
  'c', 
 
  'aaa', 
  'aaa', 
  'c', 
  'b', 
  'b', 
  'aaa', 
  'aaa'] 
 
   lists2 = [ 
  'look', 
  'see', 
  'aaa', 
  'b', 
  'c', 
 
  'aaa', 
  'aaa', 
  'c', 
  'b', 
  'b', 
  'aaa', 
  'aaa'] 
 
  from collections 
  import Counter 
 
   word_counts = Counter(lists) 
 
   top_three = word_counts.most_common( 
  3) 
 
  print(top_three) 
 
  print(word_counts[ 
  'aaa']) 
 
  ''' 
 
  [('aaa', 6), ('b', 3), ('c', 2)] 
 
  6 
 
  ''' 
 
   word2_counts = Counter(lists2) 
 
  print(word2_counts) 
 
  ''' 
 
  >>>  
  Counter({'aaa': 5, 'b': 3, 'c': 2, 'look': 1, 'see': 1}) 
 
  主要是我们的counter对象是可以进行各种数学运算操作结合起来使用 
 
  ''' 
 
   a = word_counts + word2_counts 
 
   b = word_counts - word2_counts 
 
  print(a) 
 
  print(b) 
 
  ''' 
 
  >>>Counter({'aaa': 11, 'b': 6, 'c': 4, 'look': 2, 'see': 2}) 
 
  >>>Counter({'aaa': 1}) 
 
  ''' 
 
  ''' 
 
  我们拿到源码 
 
   def most_common(self, n=None): 
 
   List the n most common elements and their counts from the most 
 
   common to the least. If n is None, then list all element counts. 
 
  >>>  
  Counter('abcdeabcdabcaba').most_common(3) 
 
   [('a', 5), ('b', 4), ('c', 3)] 
 
   # Emulate Bag.sortedByCount from Smalltalk 
 
   if n is None: 
 
   return sorted(self.items(), key=_itemgetter(1), reverse=True) 
 
   return _heapq.nlargest(n, self.items(), key=_itemgetter(1)) 
 
  源码暂时贴在这里 我还不能理解  
 
  '''