统计数列中元素的频度

from random import randint

#找出出现次数最多的前3个
data = [randint(0,20) for _ in range(30)]
print(data)
d = dict.fromkeys(data,1)
print(d)
for x in data:
    d[x] += 1

dd = sorted([(v,k) for k,v in d.items()],reverse=True)
print(dd)
print(dd[:3])

#堆
import heapq
aa = heapq.nlargest(3,((v,k) for k,v in d.items()))
print(aa)

from collections import Counter
d=Counter(data)
print(d.most_common(3))