这将给予你适当的结果

import csv
from os import name
from statistics import mean

#open both file here
with open(input_file_name) as f, open(output_file_name, 'w' , newline='') as new_f:
    #initialize writer 
    writer = csv.writer(new_f)
    
    #initialize reader
    reader = csv.reader(f)

    for row in reader:
        name = row[0]
        grades = row[1:]
        these_grades1 = list()
        for grade in grades:
            these_grades1.append(int(grade))
            # you don't need to calculate mean here 
        
        # calculate mean
        mean1 = mean(these_grades1)

        # write to file
        writer.writerow([name, float(mean1)])

字符串
更多Python版本：

import csv
from statistics import mean

with open(input_file_name) as f, open(output_file_name, 'w',
                                      newline='') as new_f:
    #initialize writer
    writer = csv.writer(new_f)

    #initialize reader
    reader = csv.reader(f)
    writer.writerows([[row[0], mean(map(int, row[1:]))] for row in reader])

型

代码中有几个错误：

• 你保留了mean1，这意味着每次读取一个新学生时，每个学生的平均值都会丢失。使用列表来跟踪已经计算的平均值（在我的代码中是result）。
• 不确定为什么在打印输出时忽略reader
• writerow接受一个列表作为输入，而不是一个字符串（如果你使用字符串，它会非常奇怪地打印出来）

下面是一个固定版本：

import csv
from os import name

result = []
with open(input_file_name) as f:
    reader = csv.reader(f)
    for row in reader:
        name = row[0]
        grades = row[1:]
        for i, grade in enumerate(grades):
            grades[i] = int(grade)
        mean = sum(grades)/len(grades)
        result.append([name, mean])

with open(output_file_name, 'w' , newline='') as new_f:
    writer = csv.writer(new_f)
    for row in result:
        writer.writerow(row)

字符串
你也可以在没有列表的情况下这样做：

import csv
from os import name

with open(input_file_name) as f, open(output_file_name, 'w' , newline='') as new_f:
    reader = csv.reader(f)
    writer = csv.writer(new_f)
    for row in reader:
        name = row[0]
        grades = row[1:]
        for i, grade in enumerate(grades):
            grades[i] = int(grade)
        mean = sum(grades)/len(grades)
        writer.writerow([name, mean])

型