Python 无法将数据写入csv文件

我无法将数据写入csv文件。我能够分离标题并添加新列，还能够添加总分，但似乎不起作用

源文件

name,Homework_1,Homework_2
Naveed,20,19
Mahvish,10,18

name,Homework_1,Homework_2,total
Mahvish,10,18,28.0
Naveed,20,19,39

目标文件

name,Homework_1,Homework_2
Naveed,20,19
Mahvish,10,18

name,Homework_1,Homework_2,total
Mahvish,10,18,28.0
Naveed,20,19,39

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您正在每个循环迭代中覆盖输出文件

with open('marks_op.csv','w',newline='') as w:

应该是

with open('marks_op.csv','a',newline='') as w:

---

我已经更正了代码。谢谢你的解决方案

import csv


def letterGrade(score):
    if score >= 90:
        letter = 'A'
    elif score >= 80:
        letter = 'B'
    elif score >= 70:
       letter = 'C'
    elif score >= 60:
        letter = 'D'
    else:
        letter = 'F'  #fall through or default case
    return letter


    
with open('marks.csv','r') as r:
    csvReader=csv.reader(r)
 
    header=next(csvReader)
    header.append("total")
    
    with open('marks_op.csv','w',newline='') as w:
        csvWriter=csv.writer(w,delimiter=',')
        csvWriter.writerow(header)
   
    total=0
    if header!=None:
        for row in csvReader:
            total=0
            for index in range(1,3):
                thisGrade = row[index]
                if thisGrade == '':
                    thisGrade = 0.0  # change a nothing to a zero
                else:
                    thisGrade = float(thisGrade) 
                total = total + thisGrade
                
            percent = (total  * 100.)/ 200.  # out of a possible 200 points

            gradeToReport = letterGrade(percent)
            
        
            row.append(total)
            
            with open('marks_op.csv','a',newline='') as x:
                csvWriter=csv.writer(x,delimiter=',')
                csvWriter.writerow(row) 


        
        
        
        
            
                
            

 

---

让我在这里补充一句。。您可以从代码中看到，我已将标题和值分隔开。我能够写标题和一行值。也许是因为我把我的列表一个一个地叠在另一个上面，比如['Naveed'，'20'，'19'，39.0]['Mahvish'，'10'，'18'，28.0]。请不要加上“谢谢”作为回答。相反，你认为这是最有帮助的-