Python:计算列表中的重复元素

Question

我是Python的新手.我试图找到一种简单的方法来计算列表中重复的元素数量,例如

MyList = ["a", "b", "a", "c", "c", "a", "c"]

输出:

a: 3
b: 1
c: 3

Answer 1

你可以这样做count:

my_dict = {i:MyList.count(i) for i in MyList}

>>> print my_dict     #or print(my_dict) in python-3.x
{'a': 3, 'c': 3, 'b': 1}

或使用collections.Counter:

from collections import Counter

a = dict(Counter(MyList))

>>> print a           #or print(a) in python-3.x
{'a': 3, 'c': 3, 'b': 1}

Answer 2

使用 Counter

>>> from collections import Counter
>>> MyList = ["a", "b", "a", "c", "c", "a", "c"]
>>> c = Counter(MyList)
>>> c
Counter({'a': 3, 'c': 3, 'b': 1})

Answer 3

yourList = ["a", "b", "a", "c", "c", "a", "c"]

预期输出 {a: 3, b: 1,c:3}

duplicateFrequencies = {}
for i in set(yourList):
    duplicateFrequencies[i] = yourList.count(i)

干杯！！参考

Answer 4

In [2]: MyList = ["a", "b", "a", "c", "c", "a", "c"]

In [3]: count = {}

In [4]: for i in MyList:
   ...:     if not i in count:
   ...:         count[i] = 1
   ...:     else:
   ...:         count[i] +=1
   ...:

In [5]: count
Out[5]: {'a': 3, 'b': 1, 'c': 3}

Answer 5

这适用于Python 2.6.6

a = ["a", "b", "a"]
result = dict((i, a.count(i)) for i in a)
print result

版画

{'a': 2, 'b': 1}