授業料免除用成績平均値算出 https://gist.github.com/Yuiki/d2394e18a424f17f26b3124a3f4ff8ba の改変なのでGPAと表記していますがあしからず

gpa2.py

import csv
import sys

argv = sys.argv

if (len(argv) != 2):
    print("Usage: python3 {} gpa.csv".format(argv[0]))
    quit()

total_amount = 0
total_gp = 0

gp_map = {'A+': 5, 'A': 5, 'B': 3, 'C': 2}

filename = argv[1]

with open(filename, 'r') as f:
    reader = csv.reader(f)
    header = next(reader)

    for row in reader:
        evaluation = row[6]

        if evaluation in ['P', 'F', 'D']: continue

        gp = gp_map.get(evaluation, 0)

        amount = float(row[5])

        total_amount += amount
        total_gp += gp * amount

print("Your GPA is {}.".format(total_gp / total_amount))