How to write in a specific cell in a CSV file?

Question

I have an asignment in which I need to imput random grades of different students in a csv file using Python 3, and get the average of each student(the average thing and how to get the random grades, I know how to do it), the thing is that I don't know how to write the grades on those specific columns and rows(highlighted ones).

Highlighted area is the space in which I need to write random grades:

Is there anyway that this can be done? I'm fairly new to programming and Python 3, and as far as I've read, specifics cells can't be changed using normal means.

Answer 1

csv module doesn't have functions to modify specific cells.

You can read rows from original file, append grades and write modified rows to new file:

import random
import csv

inputFile = open('grades.csv', 'r')
outputFile = open('grades_out.csv', 'w')
reader = csv.reader(inputFile)
writer = csv.writer(outputFile)
for row in reader:
    grades = row.copy()
    for i in range(5):
        grades.append(random.randint(1, 5))
    writer.writerow(grades)
inputFile.close()
outputFile.close()

Then you can delete original file and rename new file (it is not good to read the whole original file to a variable, close it, open it again in writing mode and then write data, because it can be big).