1-3如何统计序列元素出现的次数

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统计序列

Python 字典(Dictionary) fromkeys() 函数用于创建一个新字典，以序列seq中元素做字典的键，value为字典所有键对应的初始值。

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from random import randint
from collections import Counter

data = [randint(0, 20) for _ in range(50)]
# 以data为key, 默认为0的字典
c = dict.fromkeys(data, 0)

for x in data:
    c[x] += 1

c2 = Counter(data)
# 取出次数最多的3个
print(c2.most_common(3))

统计出现的单词数

from collections import Counter
import re

txt = open("quick_sort.py").read()

data = re.split("\W+", txt)
c = Counter(data)

print(c.most_common(2))