2-2 3 4 命名、统计、字典

如何为元组中的每个元素命名，提高程序的可读性

from collections import namedtuple

# 通常需要采用下标访问元素
student = ("Jim", 18, "male", "[email protected]")
# 1.采用常量定义
NAME, AGE, SEX, EMAIL = range(4)
# 2.采用nametuple
Student = namedtuple("Student", ["name", "age", "sex", "email"])
s = Student("Jim", 18, "male", "[email protected]")


if __name__ == "__main__":
    print(student[NAME], student[AGE])
    print(s.name, s.age)
    print(isinstance(s, tuple))

如何统计序列中元素出现的频度

1. 某随机序列中，找出出现次数最高的三个元素，它们出现了多少次？
2. 对某英文文章的单词，进行词频统计，找出出现次数最高的10个单词，它们出现了多少次？

import re
from random import randint
from collections import Counter

data = [randint(0, 20) for _ in range(100)]

c = dict.fromkeys(data, 0)
# c = dict.fromkeys(range(0, 21), 0)  # 此处注意需要包括20

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

c2 = Counter(data)

txt = open("doc.txt", "r").read()
c3 = Counter(re.split("\W+", txt))

if __name__ == "__main__":
    print(c)
    print(c2)
    print(c2.most_common(3))

    print(c3)
    print(c3.most_common(10))

字典

如何根据字典中值的大小，对字典中的项进行排序
某班英语成绩以字典的形式进行存储，根据成绩高低进行排名

from random import randint

student = {x: randint(50, 100) for x in "xyzabc"}

sor = sorted(zip(student.values(), student.keys()))

sor2 = sorted(student.items(), key=lambda x: x[1])

sor3 = sorted(student.items(), key=lambda x: x[1], reverse=True)

if __name__ == "__main__":
    print(sor)
    print(sor2)
    # 降序排列
    print(sor3)