Python 3はシーケンス内の要素の出現頻度をどのように統計するか

#!/usr/bin/env python3
# -*- coding: UTF-8 -*-

from random import randint

data = [randint(0, 20) for _ in range(30)]

1.反復

'''     '''
#          ，        ，     0
d = {}
for i in data:
    d[i] = 0

#         fromkeys()   
#     seq         ，value             
# d = dict.fromkeys(data, 0)

#               ，            1
for i in data:
    d[i] += 1
print(d)
    
'''     '''
#      get()          ，             
d2 = {}
for i in data:
    d2[i] = d2.get(i, 0) + 1
print(d2)

2.標準ライブラリのcollections.Counterを使用して要素の出現頻度を統計する

from collections import Counter

d3 = Counter(data)

print(dict(d3))
# most_common(3)         3   
print(d3.most_common(3))

実行結果:

Geek-Mac:Downloads zhangyi$ python3 Nice.py 
{5: 3, 19: 2, 20: 1, 15: 2, 10: 4, 3: 2, 2: 3, 8: 1, 1: 4, 4: 2, 7: 1, 18: 1, 16: 1, 9: 1, 6: 1, 0: 1}
{5: 3, 19: 2, 20: 1, 15: 2, 10: 4, 3: 2, 2: 3, 8: 1, 1: 4, 4: 2, 7: 1, 18: 1, 16: 1, 9: 1, 6: 1, 0: 1}
{5: 3, 19: 2, 20: 1, 15: 2, 10: 4, 3: 2, 2: 3, 8: 1, 1: 4, 4: 2, 7: 1, 18: 1, 16: 1, 9: 1, 6: 1, 0: 1}
[(10, 4), (1, 4), (5, 3)]