Python TypeError: string indices must be integers报错排查求助

处理第一条学生记录（arto）时代码运行正常，但处理第二条记录（erkki）时触发TypeError: string indices must be integers, not 'str'，错误出在print(maxs>wank[line[0]])语句。

报错追踪 #

Traceback (most recent call last):
  File "c:\Users\User\AppData\Local\tmc\vscode\mooc-programming-24\part07-15_who_cheated_2\src\who_cheated_2.py", line 51, in <module>    
    print(final_points())
          ^^^^^^^^^^^^^^
  File "c:\Users\User\AppData\Local\tmc\vscode\mooc-programming-24\part07-15_who_cheated_2\src\who_cheated_2.py", line 29, in final_points
    print(maxs>wank[line[0]])
               ~~~~^^^^^^^^^
TypeError: string indices must be integers, not 'str'

代码实现 #

# Write your solution here

from datetime import timedelta,datetime
import csv


def final_points():
    wank = {}
    with open("start_times.csv") as rocky:
        for line in csv.reader(rocky,delimiter=";"):
            pol = datetime.strptime(line[1],"%H:%M")
            wank[line[0]] = pol

                    
    students = {}
    rankings = {"1":0,"2":0,"3":0,"4":0,"5":0,"6":0,"7":0,"8":0}
    
    
    with open("submissions.csv") as monks:
        for line in csv.reader(monks,delimiter=";"):
            rap = datetime.strptime(line[3],"%H:%M")
            
            maxs = rap - timedelta(hours=3)
            print(line[0])
            print(maxs>wank[line[0]])
            if maxs>wank[line[0]]:
                continue
            
            
            
            wank = line[1]
            if line[0] not in students:
                students[line[0]] = rankings
            print(students)
            
            if students[line[0]][line[1]]<int(line[2]):
                students[line[0]][line[1]] = int(line[2])
            
        for key in students:
            students[key] = sum(students[key].values())

    
    return students


if __name__ == "__main__":
    print(final_points())

CSV文件格式 #

start_times.csv #

matti;13:33
erkki;15:13
antti;15:49
emilia;13:37
henrik;15:01
arto;17:01
esko;14:24
kjell;13:34
jyrki;16:12
etc..

submissions.csv #

arto;1;4;19:12
erkki;2;2;16:03
matti;7;3;16:21
jyrki;1;3;17:43
etc...

问题原因与修复方案 #

核心错误1：字典被意外覆盖 #

代码中wank原本是存储学生开始时间的字典，但在处理submissions.csv的循环里，你写了wank = line[1]，这直接把wank从字典改成了当前行的作业编号字符串（比如处理arto时，wank变成了"1"）。处理第一条记录时wank还是字典，所以正常；到第二条erkki时，wank已经是字符串，执行wank[line[0]]就会报错——字符串的索引只能是整数，而line[0]是学生名字字符串，触发TypeError。

核心错误2：共享字典导致数据混乱 #

students[line[0]] = rankings是直接引用同一个rankings字典，所有学生的分数会共享这个字典，修改一个学生的分数会影响所有学生，必须改为创建字典的副本。

修复后的代码 #

from datetime import timedelta, datetime
import csv


def final_points():
    # 存储学生的开始时间，键是学生名，值是datetime对象
    start_times = {}
    with open("start_times.csv") as rocky:
        for line in csv.reader(rocky, delimiter=";"):
            start_time = datetime.strptime(line[1], "%H:%M")
            start_times[line[0]] = start_time

    students = {}
    # 每个学生的作业初始分数模板
    score_template = {"1": 0, "2": 0, "3": 0, "4": 0, "5": 0, "6": 0, "7": 0, "8": 0}

    with open("submissions.csv") as monks:
        for line in csv.reader(monks, delimiter=";"):
            student_name = line[0]
            exercise_num = line[1]
            score = int(line[2])
            submit_time = datetime.strptime(line[3], "%H:%M")

            # 计算提交时间的3小时前，判断是否超过开始时间
            three_hours_before = submit_time - timedelta(hours=3)
            if three_hours_before > start_times[student_name]:
                continue

            # 为学生创建独立的分数字典（用副本，避免共享）
            if student_name not in students:
                students[student_name] = score_template.copy()

            # 更新对应作业的最高分数
            if students[student_name][exercise_num] < score:
                students[student_name][exercise_num] = score

        # 计算每个学生的总分
        for student in students:
            students[student] = sum(students[student].values())

    return students


if __name__ == "__main__":
    print(final_points())

修复说明 #

1. 重命名wank为start_times，变量名更清晰，避免混淆。
2. 删除了错误的wank = line[1]语句，不再覆盖存储开始时间的字典。
3. 将students[line[0]] = rankings改为students[student_name] = score_template.copy()，每个学生拥有独立的分数字典，避免数据互相影响。
4. 拆分了line的元素到单独变量，代码可读性更高。

内容的提问来源于stack exchange，提问作者Jaime III Andrade