【2.1.4】python列表--查找集合中重复元素的个数(count)

1. count

>>> mylist = [1,2,2,2,2,3,3,3,4,4,4,4]
>>> myset = set(mylist)
>>> for item in myset:
        print("the %d has found %d" %(item,mylist.count(item)))

the 1 has found 1
the 2 has found 4
the 3 has found 3
the 4 has found 4

2. Counter

>>> from collections import Counter
>>> Counter([1,2,2,2,2,3,3,3,4,4,4,4])
Counter({2: 4, 4: 4, 3: 3, 1: 1})

如果输出数量最多的4个元素,可以

high_common = Counter([1,2,2,2,2,3,3,3,4,4,4,4]).most_common(4)

3.dict

data = [1,2,3,4,2,3,4,2,3,4,5,6,6,4,4,5,6,7,4]
data_dict = {}
for key in data:
    data_dict[key] = data_dict.get(key,0) + 1
print("data_dict:",data_dict)

输出结果:

data_dict: {1: 1, 2: 3, 3: 3, 4: 6, 5: 2, 6: 3, 7: 1}

4. pd.value_counts

import pandas as pd
data = [1,2,3,4,2,3,4,2,3,4,5,6,6,4,4,5,6,7,4]
result = pd.value_counts(data)
print("result:",result)

输出结果:

result: 4 6
6 3
3 3
2 3
5 2
7 1
1 1
dtype: int64

参考资料

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