Score rating of 100 classic python questions

Question: Students with academic scores >= 90 points are represented by A, students with scores between 60-89 are represented by B, and students with scores below 60 are represented by C.

Option 1: Use if statement to determine

1. Use Python's built-in open() function to open the txt file, use the read() method to read the contents of the file, and use the splitlines() method to split each line.
2. Traverse each row, judge the score of each student, divide it into three categories: A, B, and C based on the score, and splice the rating results to the end of each row
3. Use the write() method to write the rated content back to the txt file

Advantages: Simple to implement and easy to understand

Disadvantages: The code has poor readability. When the judgment conditions are many and complex, the amount of code will increase and it will be difficult to maintain.

with open('scores.txt', 'r') as f:
    lines = f.readlines()  # 读取所有行

with open('scores.txt', 'w') as f:
    for line in lines:
        score = int(line.strip())  # 去除换行符并转为整数
        if score >= 90:
            level = 'A'
        elif score >= 60:
            level = 'B'
        else:
            level = 'C'
        f.write('{} {}\n'.format(line.strip(), level))  # 写入原始分数和评级
 

Option 2: Use list comprehensions and lambda functions

1. Use Python's built-in open() function to open the txt file, use the read() method to read the contents of the file, and use the splitlines() method to split each line.
2. Traverse each row, use list derivation and lambda function to judge the score of each student, divide it into three categories: A, B, and C according to the score, and splice the rating results to the end of each row
3. Use the write() method to write the rated content back to the txt file

Advantages: The code is concise, highly readable, and suitable for some simple data operations.

Disadvantages: When the judgment conditions are complex, readability will decrease and it will be difficult to maintain.

# lambda函数用于将数值转换成对应的等级
get_grade = lambda score: 'A' if score >= 90 else ('B' if score >= 60 else 'C')

with open('scores.txt', 'r') as f:
    # 读取每一行并根据空格分割成列表
    scores = [line.strip().split() for line in f.readlines()]

# 将每个学生的成绩转换成对应的等级，并将结果追加到列表中
grades = [[*score, get_grade(int(score[-1]))] for score in scores]

with open('grades.txt', 'w') as f:
    # 将每个学生的信息写入文件中
    for grade in grades:
        f.write(' '.join(grade) + '\n')
 

Option 3: Use the pandas library for data processing

1. Read txt files using the read_csv() method of the pandas library
2. Use the apply() method to judge the score of each student, divide it into three categories: A, B, and C based on the score, and add the rating results to a new column.
3. Use the to_csv() method to write the processed data back to the txt file

Advantages: The pandas library has powerful data processing capabilities, can perform data operations quickly and efficiently, and the code is highly readable.

Disadvantages: For simple data operations, using the pandas library is a bit too complicated, and you need to install the third-party library pandas

import pandas as pd

# 读取txt文件，假设文件中有两列，分别为name和score
df = pd.read_table('data.txt', sep='\s+', header=None, names=['name', 'score'])

# 定义评级函数
def get_grade(score):
    if score >= 90:
        return 'A'
    elif score >= 60:
        return 'B'
    else:
        return 'C'

# 添加评级列
df['grade'] = df['score'].apply(get_grade)

# 根据评级列进行排序
df.sort_values(by=['grade'], ascending=False, inplace=True)

# 将结果写入txt文件
df.to_csv('result.txt', index=False, sep='\t', header=None)