python 中实现对列表中各元素的个数进行统计

001、 方法1

>>> list1 = ["aa", "aa", "bb", "aa", "cc", "cc"]        ## 测试列表
>>> list1.count("aa")                                   ## 借助内置函数输出单个元素的次数
3
>>> set(list1)                                          ## 利用集合去重复
{'cc', 'aa', 'bb'}
>>> for i in set(list1):                                ## 借助循环结构统计每个元素出现的次数
...     print(i, list1.count(i))
...
cc 2
aa 3
bb 1

002、方法2 借助字典统计

>>> list1 = ["aa", "aa", "bb", "aa", "cc", "cc"]          ## 测试列表
>>> dict1 = dict()                                        ## 借助字典统计
>>> for i in list1:
...     if i not in dict1:
...             dict1[i] = 1
...     else:
...             dict1[i] += 1
...
>>> for i in dict1:
...     print(i, dict1[i])
...
aa 3
bb 1
cc 2

003、借助内置模块 counter

>>> list1 = ["aa", "aa", "bb", "aa", "cc", "cc"]
>>> from collections import Counter                  ## 借助内置模块统计
>>> count = Counter(list1)
>>> for i in count:
...     print(i, count[i])
...
aa 3
bb 1
cc 2

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