Python用字母grad替换CSV文件中的整数

Question

所以我在BSU的CS课程中，这里的作业是读取一个CSV文件，其中包含了课程名称、这些课程的分数以及该课程的学时。我们被告知要用适当的字母分数来代替班级的分数，但我正在努力想办法？如果有人知道如何轻松地将一些东西集成到这里，我可以用字母等级替换csv文件中的整数

import csv

courses = []
with open("courses.csv") as file:
    reader = csv.reader(file, delimiter=",")
    for row in reader:
        print(row)

def read_csv(file):
    courses = []
    with open(file) as file:
        reader = csv.reader(file, delimiter='.')
        next(reader)
        for row in reader:
            courses.append(row)
    return courses

def print_scores():
    i=0
    file = "courses.csv"
    courses = read_csv(file)
    print("{0:10} {1:10} {2:10}".format("Course", "Score", "Cerdits"))
    for row in file:
        score = row[i][1]
        row[i][1] = grade(score)
        i += 1


def grade(score):
    if score > 100:
        grade = "Doesn't matter, ur a nurd"
    elif score >= 90:
        grade = "A"
    elif score >= 80:
        grade = "B"
    elif score >= 70:
        grade = "C"
    elif score >= 60:
        grade = "D"
    else:
        grade = "F"
    return grade