python函数：Couter(x).most_common(n)

Counter(x)

统计x中各元素出现次数

Counter(x).most_common(3)

出现次数最多的前n个元素及其次数

from collections import Counter
str = "ashduioashfahuoif"
result = Counter(str).most_common(3)
print(result)   #[('a', 3), ('h', 3), ('s', 2)]
cout = Counter(str)
print(cout)     
#Counter({'a': 3, 'h': 3, 's': 2, 'u': 2, 'i': 2, 'o': 2, 'f': 2, 'd': 1})
print(cout['a'])    #3

list_test = [1,2,3,4,5,1,1,1,2,2,3]
cout_1 = Counter(list_test)
result_1 = cout_1.most_common(3)
print(result_1) #[(1, 4), (2, 3), (3, 2)]